+
+
+
+
A collection of async functions for manipulating collections, such as
+arrays and objects.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Methods
+
+
+
+
+
+
+ (static) concat(coll, iteratee, callbackopt)
+
+
+
+
+
+
+
import concat from 'async/concat';
+
+
Applies iteratee to each item in coll, concatenating the results. Returns
+the concatenated list. The iteratees are called in parallel, and the
+results are concatenated as they return. The results array will be returned in
+the original order of coll passed to the iteratee function.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each item in coll,
+which should use an array as its result. Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished, or an error occurs. Results is an array
+containing the concatenated results of the iteratee function. Invoked with
+(err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
A Promise, if no callback is passed
+
Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+// dir4 does not exist
+
+let directoryList = ['dir1','dir2','dir3'];
+let withMissingDirectoryList = ['dir1','dir2','dir3', 'dir4'];
+
+// Using callbacks
+async.concat(directoryList, fs.readdir, function(err, results) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(results);
+ // [ 'file1.txt', 'file2.txt', 'file3.txt', 'file4.txt', file5.txt ]
+ }
+});
+
+// Error Handling
+async.concat(withMissingDirectoryList, fs.readdir, function(err, results) {
+ if (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ // since dir4 does not exist
+ } else {
+ console.log(results);
+ }
+});
+
+// Using Promises
+async.concat(directoryList, fs.readdir)
+.then(results => {
+ console.log(results);
+ // [ 'file1.txt', 'file2.txt', 'file3.txt', 'file4.txt', file5.txt ]
+}).catch(err => {
+ console.log(err);
+});
+
+// Error Handling
+async.concat(withMissingDirectoryList, fs.readdir)
+.then(results => {
+ console.log(results);
+}).catch(err => {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ // since dir4 does not exist
+});
+
+// Using async/await
+async () => {
+ try {
+ let results = await async.concat(directoryList, fs.readdir);
+ console.log(results);
+ // [ 'file1.txt', 'file2.txt', 'file3.txt', 'file4.txt', file5.txt ]
+ } catch (err) {
+ console.log(err);
+ }
+}
+
+// Error Handling
+async () => {
+ try {
+ let results = await async.concat(withMissingDirectoryList, fs.readdir);
+ console.log(results);
+ } catch (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ // since dir4 does not exist
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) concatLimit(coll, limit, iteratee, callbackopt)
+
+
+
+
+
+
+
import concatLimit from 'async/concatLimit';
+
+
The same as concat but runs a maximum of limit async operations at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each item in coll,
+which should use an array as its result. Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished, or an error occurs. Results is an array
+containing the concatenated results of the iteratee function. Invoked with
+(err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
A Promise, if no callback is passed
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) concatSeries(coll, iteratee, callbackopt)
+
+
+
+
+
+
+
import concatSeries from 'async/concatSeries';
+
+
The same as concat but runs only a single async operation at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each item in coll.
+The iteratee should complete with an array an array of results.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished, or an error occurs. Results is an array
+containing the concatenated results of the iteratee function. Invoked with
+(err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
A Promise, if no callback is passed
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) detect(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import detect from 'async/detect';
+
+
Returns the first value in coll that passes an async truth test. The
+iteratee is applied in parallel, meaning the first iteratee to return
+true will fire the detect callback with that result. That means the
+result might not be the first item in the original coll (in terms of order)
+that passes the test.
+If order within the original coll is important, then look at
+detectSeries.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A truth test to apply to each item in coll.
+The iteratee must complete with a boolean value as its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called as soon as any
+iteratee returns true, or after all the iteratee functions have finished.
+Result will be the first item in the array that passes the truth test
+(iteratee) or the value undefined if none passed. Invoked with
+(err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+
+// asynchronous function that checks if a file exists
+function fileExists(file, callback) {
+ fs.access(file, fs.constants.F_OK, (err) => {
+ callback(null, !err);
+ });
+}
+
+async.detect(['file3.txt','file2.txt','dir1/file1.txt'], fileExists,
+ function(err, result) {
+ console.log(result);
+ // dir1/file1.txt
+ // result now equals the first file in the list that exists
+ }
+);
+
+// Using Promises
+async.detect(['file3.txt','file2.txt','dir1/file1.txt'], fileExists)
+.then(result => {
+ console.log(result);
+ // dir1/file1.txt
+ // result now equals the first file in the list that exists
+}).catch(err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.detect(['file3.txt','file2.txt','dir1/file1.txt'], fileExists);
+ console.log(result);
+ // dir1/file1.txt
+ // result now equals the file in the list that exists
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) detectLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import detectLimit from 'async/detectLimit';
+
+
The same as detect but runs a maximum of limit async operations at a
+time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A truth test to apply to each item in coll.
+The iteratee must complete with a boolean value as its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called as soon as any
+iteratee returns true, or after all the iteratee functions have finished.
+Result will be the first item in the array that passes the truth test
+(iteratee) or the value undefined if none passed. Invoked with
+(err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) detectSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import detectSeries from 'async/detectSeries';
+
+
The same as detect but runs only a single async operation at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A truth test to apply to each item in coll.
+The iteratee must complete with a boolean value as its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called as soon as any
+iteratee returns true, or after all the iteratee functions have finished.
+Result will be the first item in the array that passes the truth test
+(iteratee) or the value undefined if none passed. Invoked with
+(err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) each(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import each from 'async/each';
+
+
Applies the function iteratee to each item in coll, in parallel.
+The iteratee is called with an item from the list, and a callback for when
+it has finished. If the iteratee passes an error to its callback, the
+main callback (for the each function) is immediately called with the
+error.
+
Note, that since this function applies iteratee to each item in parallel,
+there is no guarantee that the iteratee functions will complete in order.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to
+each item in coll. Invoked with (item, callback).
+The array index is not passed to the iteratee.
+If you need the index, use eachOf. |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all
+iteratee functions have finished, or an error occurs. Invoked with (err). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+// dir4 does not exist
+
+const fileList = [ 'dir1/file2.txt', 'dir2/file3.txt', 'dir/file5.txt'];
+const withMissingFileList = ['dir1/file1.txt', 'dir4/file2.txt'];
+
+// asynchronous function that deletes a file
+const deleteFile = function(file, callback) {
+ fs.unlink(file, callback);
+};
+
+// Using callbacks
+async.each(fileList, deleteFile, function(err) {
+ if( err ) {
+ console.log(err);
+ } else {
+ console.log('All files have been deleted successfully');
+ }
+});
+
+// Error Handling
+async.each(withMissingFileList, deleteFile, function(err){
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ // since dir4/file2.txt does not exist
+ // dir1/file1.txt could have been deleted
+});
+
+// Using Promises
+async.each(fileList, deleteFile)
+.then( () => {
+ console.log('All files have been deleted successfully');
+}).catch( err => {
+ console.log(err);
+});
+
+// Error Handling
+async.each(fileList, deleteFile)
+.then( () => {
+ console.log('All files have been deleted successfully');
+}).catch( err => {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ // since dir4/file2.txt does not exist
+ // dir1/file1.txt could have been deleted
+});
+
+// Using async/await
+async () => {
+ try {
+ await async.each(files, deleteFile);
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+// Error Handling
+async () => {
+ try {
+ await async.each(withMissingFileList, deleteFile);
+ }
+ catch (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ // since dir4/file2.txt does not exist
+ // dir1/file1.txt could have been deleted
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) eachLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import eachLimit from 'async/eachLimit';
+
+
The same as each but runs a maximum of limit async operations at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The array index is not passed to the iteratee.
+If you need the index, use eachOfLimit.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all
+iteratee functions have finished, or an error occurs. Invoked with (err). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) eachOf(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import eachOf from 'async/eachOf';
+
+
Like each, except that it passes the key (or index) as the second argument
+to the iteratee.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each
+item in coll.
+The key is the item's key, or index in the case of an array.
+Invoked with (item, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all
+iteratee functions have finished, or an error occurs. Invoked with (err). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dev.json is a file containing a valid json object config for dev environment
+// dev.json is a file containing a valid json object config for test environment
+// prod.json is a file containing a valid json object config for prod environment
+// invalid.json is a file with a malformed json object
+
+let configs = {}; //global variable
+let validConfigFileMap = {dev: 'dev.json', test: 'test.json', prod: 'prod.json'};
+let invalidConfigFileMap = {dev: 'dev.json', test: 'test.json', invalid: 'invalid.json'};
+
+// asynchronous function that reads a json file and parses the contents as json object
+function parseFile(file, key, callback) {
+ fs.readFile(file, "utf8", function(err, data) {
+ if (err) return calback(err);
+ try {
+ configs[key] = JSON.parse(data);
+ } catch (e) {
+ return callback(e);
+ }
+ callback();
+ });
+}
+
+// Using callbacks
+async.forEachOf(validConfigFileMap, parseFile, function (err) {
+ if (err) {
+ console.error(err);
+ } else {
+ console.log(configs);
+ // configs is now a map of JSON data, e.g.
+ // { dev: //parsed dev.json, test: //parsed test.json, prod: //parsed prod.json}
+ }
+});
+
+//Error handing
+async.forEachOf(invalidConfigFileMap, parseFile, function (err) {
+ if (err) {
+ console.error(err);
+ // JSON parse error exception
+ } else {
+ console.log(configs);
+ }
+});
+
+// Using Promises
+async.forEachOf(validConfigFileMap, parseFile)
+.then( () => {
+ console.log(configs);
+ // configs is now a map of JSON data, e.g.
+ // { dev: //parsed dev.json, test: //parsed test.json, prod: //parsed prod.json}
+}).catch( err => {
+ console.error(err);
+});
+
+//Error handing
+async.forEachOf(invalidConfigFileMap, parseFile)
+.then( () => {
+ console.log(configs);
+}).catch( err => {
+ console.error(err);
+ // JSON parse error exception
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.forEachOf(validConfigFileMap, parseFile);
+ console.log(configs);
+ // configs is now a map of JSON data, e.g.
+ // { dev: //parsed dev.json, test: //parsed test.json, prod: //parsed prod.json}
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+//Error handing
+async () => {
+ try {
+ let result = await async.forEachOf(invalidConfigFileMap, parseFile);
+ console.log(configs);
+ }
+ catch (err) {
+ console.log(err);
+ // JSON parse error exception
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) eachOfLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import eachOfLimit from 'async/eachOfLimit';
+
+
The same as eachOf but runs a maximum of limit async operations at a
+time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each
+item in coll. The key is the item's key, or index in the case of an
+array.
+Invoked with (item, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all
+iteratee functions have finished, or an error occurs. Invoked with (err). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) eachOfSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import eachOfSeries from 'async/eachOfSeries';
+
+
The same as eachOf but runs only a single async operation at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+Invoked with (item, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Invoked with (err). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) eachSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import eachSeries from 'async/eachSeries';
+
+
The same as each but runs only a single async operation at a time.
+
Note, that unlike each, this function applies iteratee to each item
+in series and therefore the iteratee functions will complete in order.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each
+item in coll.
+The array index is not passed to the iteratee.
+If you need the index, use eachOfSeries.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all
+iteratee functions have finished, or an error occurs. Invoked with (err). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if a callback is omitted
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) every(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import every from 'async/every';
+
+
Returns true if every element in coll satisfies an async test. If any
+iteratee call returns false, the main callback is immediately called.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item
+in the collection in parallel.
+The iteratee must complete with a boolean result value.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Result will be either true or false
+depending on the values of the async tests. Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+// dir4 does not exist
+
+const fileList = ['dir1/file1.txt','dir2/file3.txt','dir3/file5.txt'];
+const withMissingFileList = ['file1.txt','file2.txt','file4.txt'];
+
+// asynchronous function that checks if a file exists
+function fileExists(file, callback) {
+ fs.access(file, fs.constants.F_OK, (err) => {
+ callback(null, !err);
+ });
+}
+
+// Using callbacks
+async.every(fileList, fileExists, function(err, result) {
+ console.log(result);
+ // true
+ // result is true since every file exists
+});
+
+async.every(withMissingFileList, fileExists, function(err, result) {
+ console.log(result);
+ // false
+ // result is false since NOT every file exists
+});
+
+// Using Promises
+async.every(fileList, fileExists)
+.then( result => {
+ console.log(result);
+ // true
+ // result is true since every file exists
+}).catch( err => {
+ console.log(err);
+});
+
+async.every(withMissingFileList, fileExists)
+.then( result => {
+ console.log(result);
+ // false
+ // result is false since NOT every file exists
+}).catch( err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.every(fileList, fileExists);
+ console.log(result);
+ // true
+ // result is true since every file exists
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+async () => {
+ try {
+ let result = await async.every(withMissingFileList, fileExists);
+ console.log(result);
+ // false
+ // result is false since NOT every file exists
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) everyLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import everyLimit from 'async/everyLimit';
+
+
The same as every but runs a maximum of limit async operations at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item
+in the collection in parallel.
+The iteratee must complete with a boolean result value.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Result will be either true or false
+depending on the values of the async tests. Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) everySeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import everySeries from 'async/everySeries';
+
+
The same as every but runs only a single async operation at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item
+in the collection in series.
+The iteratee must complete with a boolean result value.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Result will be either true or false
+depending on the values of the async tests. Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) filter(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import filter from 'async/filter';
+
+
Returns a new array of all the values in coll which pass an async truth
+test. This operation is performed in parallel, but the results array will be
+in the same order as the original.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ A truth test to apply to each item in coll.
+The iteratee is passed a callback(err, truthValue), which must be called
+with a boolean argument once it has completed. Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+
+const files = ['dir1/file1.txt','dir2/file3.txt','dir3/file6.txt'];
+
+// asynchronous function that checks if a file exists
+function fileExists(file, callback) {
+ fs.access(file, fs.constants.F_OK, (err) => {
+ callback(null, !err);
+ });
+}
+
+// Using callbacks
+async.filter(files, fileExists, function(err, results) {
+ if(err) {
+ console.log(err);
+ } else {
+ console.log(results);
+ // [ 'dir1/file1.txt', 'dir2/file3.txt' ]
+ // results is now an array of the existing files
+ }
+});
+
+// Using Promises
+async.filter(files, fileExists)
+.then(results => {
+ console.log(results);
+ // [ 'dir1/file1.txt', 'dir2/file3.txt' ]
+ // results is now an array of the existing files
+}).catch(err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let results = await async.filter(files, fileExists);
+ console.log(results);
+ // [ 'dir1/file1.txt', 'dir2/file3.txt' ]
+ // results is now an array of the existing files
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) filterLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import filterLimit from 'async/filterLimit';
+
+
The same as filter but runs a maximum of limit async operations at a
+time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ A truth test to apply to each item in coll.
+The iteratee is passed a callback(err, truthValue), which must be called
+with a boolean argument once it has completed. Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) filterSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import filterSeries from 'async/filterSeries';
+
+
The same as filter but runs only a single async operation at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ A truth test to apply to each item in coll.
+The iteratee is passed a callback(err, truthValue), which must be called
+with a boolean argument once it has completed. Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Invoked with (err, results) |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) groupBy(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import groupBy from 'async/groupBy';
+
+
Returns a new object, where each value corresponds to an array of items, from
+coll, that returned the corresponding key. That is, the keys of the object
+correspond to the values passed to the iteratee callback.
+
Note: Since this function applies the iteratee to each item in parallel,
+there is no guarantee that the iteratee functions will complete in order.
+However, the values for each key in the result will be in the same order as
+the original coll. For Objects, the values will roughly be in the order of
+the original Objects' keys (but this can vary across JavaScript engines).
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with a key to group the value under.
+Invoked with (value, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Result is an Object whoses
+properties are arrays of values which returned the corresponding key. |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+// dir4 does not exist
+
+const files = ['dir1/file1.txt','dir2','dir4']
+
+// asynchronous function that detects file type as none, file, or directory
+function detectFile(file, callback) {
+ fs.stat(file, function(err, stat) {
+ if (err) {
+ return callback(null, 'none');
+ }
+ callback(null, stat.isDirectory() ? 'directory' : 'file');
+ });
+}
+
+//Using callbacks
+async.groupBy(files, detectFile, function(err, result) {
+ if(err) {
+ console.log(err);
+ } else {
+ console.log(result);
+ // {
+ // file: [ 'dir1/file1.txt' ],
+ // none: [ 'dir4' ],
+ // directory: [ 'dir2']
+ // }
+ // result is object containing the files grouped by type
+ }
+});
+
+// Using Promises
+async.groupBy(files, detectFile)
+.then( result => {
+ console.log(result);
+ // {
+ // file: [ 'dir1/file1.txt' ],
+ // none: [ 'dir4' ],
+ // directory: [ 'dir2']
+ // }
+ // result is object containing the files grouped by type
+}).catch( err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.groupBy(files, detectFile);
+ console.log(result);
+ // {
+ // file: [ 'dir1/file1.txt' ],
+ // none: [ 'dir4' ],
+ // directory: [ 'dir2']
+ // }
+ // result is object containing the files grouped by type
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) groupByLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import groupByLimit from 'async/groupByLimit';
+
+
The same as groupBy but runs a maximum of limit async operations at a time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with a key to group the value under.
+Invoked with (value, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Result is an Object whoses
+properties are arrays of values which returned the corresponding key. |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) groupBySeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import groupBySeries from 'async/groupBySeries';
+
+
The same as groupBy but runs only a single async operation at a time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with a key to group the value under.
+Invoked with (value, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Result is an Object whose
+properties are arrays of values which returned the corresponding key. |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) map(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import map from 'async/map';
+
+
Produces a new collection of values by mapping each value in coll through
+the iteratee function. The iteratee is called with an item from coll
+and a callback for when it has finished processing. Each of these callbacks
+takes 2 arguments: an error, and the transformed item from coll. If
+iteratee passes an error to its callback, the main callback (for the
+map function) is immediately called with the error.
+
Note, that since this function applies the iteratee to each item in
+parallel, there is no guarantee that the iteratee functions will complete
+in order. However, the results array will be in the same order as the
+original coll.
+
If map is passed an Object, the results will be an Array. The results
+will roughly be in the order of the original Objects' keys (but this can
+vary across JavaScript engines).
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with the transformed item.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Results is an Array of the
+transformed items from the coll. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // file1.txt is a file that is 1000 bytes in size
+// file2.txt is a file that is 2000 bytes in size
+// file3.txt is a file that is 3000 bytes in size
+// file4.txt does not exist
+
+const fileList = ['file1.txt','file2.txt','file3.txt'];
+const withMissingFileList = ['file1.txt','file2.txt','file4.txt'];
+
+// asynchronous function that returns the file size in bytes
+function getFileSizeInBytes(file, callback) {
+ fs.stat(file, function(err, stat) {
+ if (err) {
+ return callback(err);
+ }
+ callback(null, stat.size);
+ });
+}
+
+// Using callbacks
+async.map(fileList, getFileSizeInBytes, function(err, results) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(results);
+ // results is now an array of the file size in bytes for each file, e.g.
+ // [ 1000, 2000, 3000]
+ }
+});
+
+// Error Handling
+async.map(withMissingFileList, getFileSizeInBytes, function(err, results) {
+ if (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ } else {
+ console.log(results);
+ }
+});
+
+// Using Promises
+async.map(fileList, getFileSizeInBytes)
+.then( results => {
+ console.log(results);
+ // results is now an array of the file size in bytes for each file, e.g.
+ // [ 1000, 2000, 3000]
+}).catch( err => {
+ console.log(err);
+});
+
+// Error Handling
+async.map(withMissingFileList, getFileSizeInBytes)
+.then( results => {
+ console.log(results);
+}).catch( err => {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+});
+
+// Using async/await
+async () => {
+ try {
+ let results = await async.map(fileList, getFileSizeInBytes);
+ console.log(results);
+ // results is now an array of the file size in bytes for each file, e.g.
+ // [ 1000, 2000, 3000]
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+// Error Handling
+async () => {
+ try {
+ let results = await async.map(withMissingFileList, getFileSizeInBytes);
+ console.log(results);
+ }
+ catch (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) mapLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import mapLimit from 'async/mapLimit';
+
+
The same as map but runs a maximum of limit async operations at a time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with the transformed item.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Results is an array of the
+transformed items from the coll. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) mapSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import mapSeries from 'async/mapSeries';
+
+
The same as map but runs only a single async operation at a time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with the transformed item.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. Results is an array of the
+transformed items from the coll. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) mapValues(obj, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import mapValues from 'async/mapValues';
+
+
A relative of map, designed for use with objects.
+
Produces a new Object by mapping each value of obj through the iteratee
+function. The iteratee is called each value and key from obj and a
+callback for when it has finished processing. Each of these callbacks takes
+two arguments: an error, and the transformed item from obj. If iteratee
+passes an error to its callback, the main callback (for the mapValues
+function) is immediately called with the error.
+
Note, the order of the keys in the result is not guaranteed. The keys will
+be roughly in the order they complete, (but this is very engine-specific)
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ obj |
+
+
+
+
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each value and key
+in coll.
+The iteratee should complete with the transformed value as its result.
+Invoked with (value, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. result is a new object consisting
+of each key from obj, with each transformed value on the right-hand side.
+Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // file1.txt is a file that is 1000 bytes in size
+// file2.txt is a file that is 2000 bytes in size
+// file3.txt is a file that is 3000 bytes in size
+// file4.txt does not exist
+
+const fileMap = {
+ f1: 'file1.txt',
+ f2: 'file2.txt',
+ f3: 'file3.txt'
+};
+
+const withMissingFileMap = {
+ f1: 'file1.txt',
+ f2: 'file2.txt',
+ f3: 'file4.txt'
+};
+
+// asynchronous function that returns the file size in bytes
+function getFileSizeInBytes(file, key, callback) {
+ fs.stat(file, function(err, stat) {
+ if (err) {
+ return callback(err);
+ }
+ callback(null, stat.size);
+ });
+}
+
+// Using callbacks
+async.mapValues(fileMap, getFileSizeInBytes, function(err, result) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(result);
+ // result is now a map of file size in bytes for each file, e.g.
+ // {
+ // f1: 1000,
+ // f2: 2000,
+ // f3: 3000
+ // }
+ }
+});
+
+// Error handling
+async.mapValues(withMissingFileMap, getFileSizeInBytes, function(err, result) {
+ if (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ } else {
+ console.log(result);
+ }
+});
+
+// Using Promises
+async.mapValues(fileMap, getFileSizeInBytes)
+.then( result => {
+ console.log(result);
+ // result is now a map of file size in bytes for each file, e.g.
+ // {
+ // f1: 1000,
+ // f2: 2000,
+ // f3: 3000
+ // }
+}).catch (err => {
+ console.log(err);
+});
+
+// Error Handling
+async.mapValues(withMissingFileMap, getFileSizeInBytes)
+.then( result => {
+ console.log(result);
+}).catch (err => {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.mapValues(fileMap, getFileSizeInBytes);
+ console.log(result);
+ // result is now a map of file size in bytes for each file, e.g.
+ // {
+ // f1: 1000,
+ // f2: 2000,
+ // f3: 3000
+ // }
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+// Error Handling
+async () => {
+ try {
+ let result = await async.mapValues(withMissingFileMap, getFileSizeInBytes);
+ console.log(result);
+ }
+ catch (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) mapValuesLimit(obj, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import mapValuesLimit from 'async/mapValuesLimit';
+
+
The same as mapValues but runs a maximum of limit async operations at a
+time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ obj |
+
+
+
+
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each value and key
+in coll.
+The iteratee should complete with the transformed value as its result.
+Invoked with (value, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. result is a new object consisting
+of each key from obj, with each transformed value on the right-hand side.
+Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) mapValuesSeries(obj, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import mapValuesSeries from 'async/mapValuesSeries';
+
+
The same as mapValues but runs only a single async operation at a time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ obj |
+
+
+
+
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function to apply to each value and key
+in coll.
+The iteratee should complete with the transformed value as its result.
+Invoked with (value, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called when all iteratee
+functions have finished, or an error occurs. result is a new object consisting
+of each key from obj, with each transformed value on the right-hand side.
+Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) reduce(coll, memo, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import reduce from 'async/reduce';
+
+
Reduces coll into a single value using an async iteratee to return each
+successive step. memo is the initial state of the reduction. This function
+only operates in series.
+
For performance reasons, it may make sense to split a call to this function
+into a parallel map, and then use the normal Array.prototype.reduce on the
+results. This function is for situations where each step in the reduction
+needs to be async; if you can get the data before reducing it, then it's
+probably a good idea to do so.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ memo |
+
+
+
+
+
+*
+
+
+
+
+
+ |
+
+
+
+ The initial state of the reduction. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function applied to each item in the
+array to produce the next step in the reduction.
+The iteratee should complete with the next state of the reduction.
+If the iteratee completes with an error, the reduction is stopped and the
+main callback is immediately called with the error.
+Invoked with (memo, item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Result is the reduced value. Invoked with
+(err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // file1.txt is a file that is 1000 bytes in size
+// file2.txt is a file that is 2000 bytes in size
+// file3.txt is a file that is 3000 bytes in size
+// file4.txt does not exist
+
+const fileList = ['file1.txt','file2.txt','file3.txt'];
+const withMissingFileList = ['file1.txt','file2.txt','file3.txt', 'file4.txt'];
+
+// asynchronous function that computes the file size in bytes
+// file size is added to the memoized value, then returned
+function getFileSizeInBytes(memo, file, callback) {
+ fs.stat(file, function(err, stat) {
+ if (err) {
+ return callback(err);
+ }
+ callback(null, memo + stat.size);
+ });
+}
+
+// Using callbacks
+async.reduce(fileList, 0, getFileSizeInBytes, function(err, result) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(result);
+ // 6000
+ // which is the sum of the file sizes of the three files
+ }
+});
+
+// Error Handling
+async.reduce(withMissingFileList, 0, getFileSizeInBytes, function(err, result) {
+ if (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ } else {
+ console.log(result);
+ }
+});
+
+// Using Promises
+async.reduce(fileList, 0, getFileSizeInBytes)
+.then( result => {
+ console.log(result);
+ // 6000
+ // which is the sum of the file sizes of the three files
+}).catch( err => {
+ console.log(err);
+});
+
+// Error Handling
+async.reduce(withMissingFileList, 0, getFileSizeInBytes)
+.then( result => {
+ console.log(result);
+}).catch( err => {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.reduce(fileList, 0, getFileSizeInBytes);
+ console.log(result);
+ // 6000
+ // which is the sum of the file sizes of the three files
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+// Error Handling
+async () => {
+ try {
+ let result = await async.reduce(withMissingFileList, 0, getFileSizeInBytes);
+ console.log(result);
+ }
+ catch (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) reduceRight(array, memo, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import reduceRight from 'async/reduceRight';
+
+
Same as reduce, only operates on array in reverse order.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ array |
+
+
+
+
+
+Array
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ memo |
+
+
+
+
+
+*
+
+
+
+
+
+ |
+
+
+
+ The initial state of the reduction. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function applied to each item in the
+array to produce the next step in the reduction.
+The iteratee should complete with the next state of the reduction.
+If the iteratee completes with an error, the reduction is stopped and the
+main callback is immediately called with the error.
+Invoked with (memo, item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Result is the reduced value. Invoked with
+(err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) reject(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import reject from 'async/reject';
+
+
The opposite of filter. Removes values that pass an async truth test.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item in
+coll.
+The should complete with a boolean value as its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+
+const fileList = ['dir1/file1.txt','dir2/file3.txt','dir3/file6.txt'];
+
+// asynchronous function that checks if a file exists
+function fileExists(file, callback) {
+ fs.access(file, fs.constants.F_OK, (err) => {
+ callback(null, !err);
+ });
+}
+
+// Using callbacks
+async.reject(fileList, fileExists, function(err, results) {
+ // [ 'dir3/file6.txt' ]
+ // results now equals an array of the non-existing files
+});
+
+// Using Promises
+async.reject(fileList, fileExists)
+.then( results => {
+ console.log(results);
+ // [ 'dir3/file6.txt' ]
+ // results now equals an array of the non-existing files
+}).catch( err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let results = await async.reject(fileList, fileExists);
+ console.log(results);
+ // [ 'dir3/file6.txt' ]
+ // results now equals an array of the non-existing files
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) rejectLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import rejectLimit from 'async/rejectLimit';
+
+
The same as reject but runs a maximum of limit async operations at a
+time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item in
+coll.
+The should complete with a boolean value as its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) rejectSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import rejectSeries from 'async/rejectSeries';
+
+
The same as reject but runs only a single async operation at a time.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item in
+coll.
+The should complete with a boolean value as its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback is passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) some(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import some from 'async/some';
+
+
Returns true if at least one element in the coll satisfies an async test.
+If any iteratee call returns true, the main callback is immediately
+called.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item
+in the collections in parallel.
+The iteratee should complete with a boolean result value.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called as soon as any
+iteratee returns true, or after all the iteratee functions have finished.
+Result will be either true or false depending on the values of the async
+tests. Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // dir1 is a directory that contains file1.txt, file2.txt
+// dir2 is a directory that contains file3.txt, file4.txt
+// dir3 is a directory that contains file5.txt
+// dir4 does not exist
+
+// asynchronous function that checks if a file exists
+function fileExists(file, callback) {
+ fs.access(file, fs.constants.F_OK, (err) => {
+ callback(null, !err);
+ });
+}
+
+// Using callbacks
+async.some(['dir1/missing.txt','dir2/missing.txt','dir3/file5.txt'], fileExists,
+ function(err, result) {
+ console.log(result);
+ // true
+ // result is true since some file in the list exists
+ }
+);
+
+async.some(['dir1/missing.txt','dir2/missing.txt','dir4/missing.txt'], fileExists,
+ function(err, result) {
+ console.log(result);
+ // false
+ // result is false since none of the files exists
+ }
+);
+
+// Using Promises
+async.some(['dir1/missing.txt','dir2/missing.txt','dir3/file5.txt'], fileExists)
+.then( result => {
+ console.log(result);
+ // true
+ // result is true since some file in the list exists
+}).catch( err => {
+ console.log(err);
+});
+
+async.some(['dir1/missing.txt','dir2/missing.txt','dir4/missing.txt'], fileExists)
+.then( result => {
+ console.log(result);
+ // false
+ // result is false since none of the files exists
+}).catch( err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.some(['dir1/missing.txt','dir2/missing.txt','dir3/file5.txt'], fileExists);
+ console.log(result);
+ // true
+ // result is true since some file in the list exists
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+async () => {
+ try {
+ let result = await async.some(['dir1/missing.txt','dir2/missing.txt','dir4/missing.txt'], fileExists);
+ console.log(result);
+ // false
+ // result is false since none of the files exists
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) someLimit(coll, limit, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import someLimit from 'async/someLimit';
+
+
The same as some but runs a maximum of limit async operations at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ limit |
+
+
+
+
+
+number
+
+
+
+
+
+ |
+
+
+
+ The maximum number of async operations at a time. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item
+in the collections in parallel.
+The iteratee should complete with a boolean result value.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called as soon as any
+iteratee returns true, or after all the iteratee functions have finished.
+Result will be either true or false depending on the values of the async
+tests. Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) someSeries(coll, iteratee, callbackopt) → {Promise}
+
+
+
+
+
+
+
import someSeries from 'async/someSeries';
+
+
The same as some but runs only a single async operation at a time.
+
+ - Alias:
+
+
+
+
+
+
+
+
+
+
+
+ Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async truth test to apply to each item
+in the collections in series.
+The iteratee should complete with a boolean result value.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called as soon as any
+iteratee returns true, or after all the iteratee functions have finished.
+Result will be either true or false depending on the values of the async
+tests. Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ - Source:
+
+
+
+
+
+
+ - See:
+ -
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ (static) sortBy(coll, iteratee, callback) → {Promise}
+
+
+
+
+
+
+
import sortBy from 'async/sortBy';
+
+
Sorts a list by the results of running each coll value through an async
+iteratee.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ An async function to apply to each item in
+coll.
+The iteratee should complete with a value to use as the sort criteria as
+its result.
+Invoked with (item, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished, or an error occurs. Results is the items
+from the original coll sorted by the values returned by the iteratee
+calls. Invoked with (err, results). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback passed
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Example
+
+ // bigfile.txt is a file that is 251100 bytes in size
+// mediumfile.txt is a file that is 11000 bytes in size
+// smallfile.txt is a file that is 121 bytes in size
+
+// asynchronous function that returns the file size in bytes
+function getFileSizeInBytes(file, callback) {
+ fs.stat(file, function(err, stat) {
+ if (err) {
+ return callback(err);
+ }
+ callback(null, stat.size);
+ });
+}
+
+// Using callbacks
+async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], getFileSizeInBytes,
+ function(err, results) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(results);
+ // results is now the original array of files sorted by
+ // file size (ascending by default), e.g.
+ // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
+ }
+ }
+);
+
+// By modifying the callback parameter the
+// sorting order can be influenced:
+
+// ascending order
+async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], function(file, callback) {
+ getFileSizeInBytes(file, function(getFileSizeErr, fileSize) {
+ if (getFileSizeErr) return callback(getFileSizeErr);
+ callback(null, fileSize);
+ });
+}, function(err, results) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(results);
+ // results is now the original array of files sorted by
+ // file size (ascending by default), e.g.
+ // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
+ }
+ }
+);
+
+// descending order
+async.sortBy(['bigfile.txt','mediumfile.txt','smallfile.txt'], function(file, callback) {
+ getFileSizeInBytes(file, function(getFileSizeErr, fileSize) {
+ if (getFileSizeErr) {
+ return callback(getFileSizeErr);
+ }
+ callback(null, fileSize * -1);
+ });
+}, function(err, results) {
+ if (err) {
+ console.log(err);
+ } else {
+ console.log(results);
+ // results is now the original array of files sorted by
+ // file size (ascending by default), e.g.
+ // [ 'bigfile.txt', 'mediumfile.txt', 'smallfile.txt']
+ }
+ }
+);
+
+// Error handling
+async.sortBy(['mediumfile.txt','smallfile.txt','missingfile.txt'], getFileSizeInBytes,
+ function(err, results) {
+ if (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ } else {
+ console.log(results);
+ }
+ }
+);
+
+// Using Promises
+async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], getFileSizeInBytes)
+.then( results => {
+ console.log(results);
+ // results is now the original array of files sorted by
+ // file size (ascending by default), e.g.
+ // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
+}).catch( err => {
+ console.log(err);
+});
+
+// Error handling
+async.sortBy(['mediumfile.txt','smallfile.txt','missingfile.txt'], getFileSizeInBytes)
+.then( results => {
+ console.log(results);
+}).catch( err => {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+});
+
+// Using async/await
+(async () => {
+ try {
+ let results = await async.sortBy(['bigfile.txt','mediumfile.txt','smallfile.txt'], getFileSizeInBytes);
+ console.log(results);
+ // results is now the original array of files sorted by
+ // file size (ascending by default), e.g.
+ // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
+ }
+ catch (err) {
+ console.log(err);
+ }
+})();
+
+// Error handling
+async () => {
+ try {
+ let results = await async.sortBy(['missingfile.txt','mediumfile.txt','smallfile.txt'], getFileSizeInBytes);
+ console.log(results);
+ }
+ catch (err) {
+ console.log(err);
+ // [ Error: ENOENT: no such file or directory ]
+ }
+}
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+ - Source:
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import transform from 'async/transform';
+
+
A relative of reduce. Takes an Object or Array, and iterates over each
+element in parallel, each step potentially mutating an accumulator value.
+The type of the accumulator defaults to the type of collection passed in.
+
Parameters:
+
+
+
+
+
+
+ | Name |
+
+
+ Type |
+
+
+
+
+ Description |
+
+
+
+
+
+
+
+
+ coll |
+
+
+
+
+
+Array
+|
+
+Iterable
+|
+
+AsyncIterable
+|
+
+Object
+
+
+
+
+
+ |
+
+
+
+ A collection to iterate over. |
+
+
+
+
+
+
+ accumulator |
+
+
+
+
+
+*
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ The initial state of the transform. If omitted,
+it will default to an empty Object or Array, depending on the type of coll |
+
+
+
+
+
+
+ iteratee |
+
+
+
+
+
+AsyncFunction
+
+
+
+
+
+ |
+
+
+
+ A function applied to each item in the
+collection that potentially modifies the accumulator.
+Invoked with (accumulator, item, key, callback). |
+
+
+
+
+
+
+ callback |
+
+
+
+
+
+function
+
+
+
+
+
+ <optional>
+
+ |
+
+
+
+ A callback which is called after all the
+iteratee functions have finished. Result is the transformed accumulator.
+Invoked with (err, result). |
+
+
+
+
+
+
+
+
+
+Returns:
+
+
+
+
a promise, if no callback provided
+
+ -
+ Type
+
+ -
+
+Promise
+
+
+
+
+
+
+
+
+ Examples
+
+ // file1.txt is a file that is 1000 bytes in size
+// file2.txt is a file that is 2000 bytes in size
+// file3.txt is a file that is 3000 bytes in size
+
+// helper function that returns human-readable size format from bytes
+function formatBytes(bytes, decimals = 2) {
+ // implementation not included for brevity
+ return humanReadbleFilesize;
+}
+
+const fileList = ['file1.txt','file2.txt','file3.txt'];
+
+// asynchronous function that returns the file size, transformed to human-readable format
+// e.g. 1024 bytes = 1KB, 1234 bytes = 1.21 KB, 1048576 bytes = 1MB, etc.
+function transformFileSize(acc, value, key, callback) {
+ fs.stat(value, function(err, stat) {
+ if (err) {
+ return callback(err);
+ }
+ acc[key] = formatBytes(stat.size);
+ callback(null);
+ });
+}
+
+// Using callbacks
+async.transform(fileList, transformFileSize, function(err, result) {
+ if(err) {
+ console.log(err);
+ } else {
+ console.log(result);
+ // [ '1000 Bytes', '1.95 KB', '2.93 KB' ]
+ }
+});
+
+// Using Promises
+async.transform(fileList, transformFileSize)
+.then(result => {
+ console.log(result);
+ // [ '1000 Bytes', '1.95 KB', '2.93 KB' ]
+}).catch(err => {
+ console.log(err);
+});
+
+// Using async/await
+(async () => {
+ try {
+ let result = await async.transform(fileList, transformFileSize);
+ console.log(result);
+ // [ '1000 Bytes', '1.95 KB', '2.93 KB' ]
+ }
+ catch (err) {
+ console.log(err);
+ }
+})();
+
+ // file1.txt is a file that is 1000 bytes in size
+// file2.txt is a file that is 2000 bytes in size
+// file3.txt is a file that is 3000 bytes in size
+
+// helper function that returns human-readable size format from bytes
+function formatBytes(bytes, decimals = 2) {
+ // implementation not included for brevity
+ return humanReadbleFilesize;
+}
+
+const fileMap = { f1: 'file1.txt', f2: 'file2.txt', f3: 'file3.txt' };
+
+// asynchronous function that returns the file size, transformed to human-readable format
+// e.g. 1024 bytes = 1KB, 1234 bytes = 1.21 KB, 1048576 bytes = 1MB, etc.
+function transformFileSize(acc, value, key, callback) {
+ fs.stat(value, function(err, stat) {
+ if (err) {
+ return callback(err);
+ }
+ acc[key] = formatBytes(stat.size);
+ callback(null);
+ });
+}
+
+// Using callbacks
+async.transform(fileMap, transformFileSize, function(err, result) {
+ if(err) {
+ console.log(err);
+ } else {
+ console.log(result);
+ // { f1: '1000 Bytes', f2: '1.95 KB', f3: '2.93 KB' }
+ }
+});
+
+// Using Promises
+async.transform(fileMap, transformFileSize)
+.then(result => {
+ console.log(result);
+ // { f1: '1000 Bytes', f2: '1.95 KB', f3: '2.93 KB' }
+}).catch(err => {
+ console.log(err);
+});
+
+// Using async/await
+async () => {
+ try {
+ let result = await async.transform(fileMap, transformFileSize);
+ console.log(result);
+ // { f1: '1000 Bytes', f2: '1.95 KB', f3: '2.93 KB' }
+ }
+ catch (err) {
+ console.log(err);
+ }
+}
+
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+ - Source:
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+
+
+ 
