JavaScript examples refactored

tshemsedinov · tshemsedinov · commit e9367a192c5d · 2016-10-10T01:00:05.000+03:00
diff --git a/JavaScript/1-memoize.js b/JavaScript/1-memoize.js
@@ -0,0 +1,31 @@
+'use strict';
+
+function memoize(fn) {
+  let cache = {};
+  return (...args) => {
+    let key = args + '';
+    let val = cache[key];
+    if (val) return val;
+    else {
+      let res = fn(...args);
+      cache[key] = res;
+      return res;
+    }
+  }
+}
+
+function sumSeq(a, b) {
+  console.log('Calculate sum');
+  let r = 0;
+  for (let i = a; i < b; i++) r += i;
+  return r;
+}
+
+let mSumSeq = memoize(sumSeq);
+
+console.log('First call mSumSeq(2, 5)');
+console.log('Value: ' + mSumSeq(2, 5));
+console.log('Second call mSumSeq(2, 5)');
+console.log('From cache: ' + mSumSeq(2, 5));
+console.log('Call mSumSeq(2, 6)');
+console.log('Calculated: ' + mSumSeq(2, 6));
diff --git a/JavaScript/2-speed.js b/JavaScript/2-speed.js
@@ -0,0 +1,35 @@
+'use strict';
+
+const LOOP = 10000;
+
+function memoize(fn) {
+  let cache = {};
+  return (...args) => {
+    let key = args + '';
+    let val = cache[key];
+    if (val) return val;
+    else {
+      let res = fn(...args);
+      cache[key] = res;
+      return res;
+    }
+  }
+}
+
+function fib(n) {
+  return (n <= 2) ? 1 : fib(n-1) + fib(n-2);
+}
+
+function speedTest(name, fn, args, count) {
+  let start = new Date().getTime();
+  for (let i = 0; i < count; i++) {
+    fn.apply(null, args);
+  }
+  let end = new Date().getTime();
+  let time = end - start;
+  console.log(name + ' * ' + count + ' : ' + time);
+}
+
+speedTest('fib(20)', fib, [20], LOOP);
+fib = memoize(fib);
+speedTest('memoized fib(20)', fib, [20], LOOP);
diff --git a/JavaScript/3-cacheSize.js b/JavaScript/3-cacheSize.js
@@ -0,0 +1,38 @@
+'use strict';
+
+function memoize(fn, length) {
+  let cache = {};
+  let counter = 0;
+  return (...args) => {
+    let key = args + '';
+    let val = cache[key];
+    let res = val ? val : fn(...args);
+    if (!val) {
+      if (++counter > length) {
+        delete cache[Object.keys(cache)[0]];
+      }
+      cache[key] = res;
+    }
+    return res;
+  }
+}
+
+function max(a, b) {
+  console.log('Calculate: ' + a + '+' + b);
+  return a > b ? a : b;
+}
+
+let mMax = memoize(max, 3);
+
+console.log('mMax(10, 8)');
+mMax(10, 8);
+console.log('mMax(1, 15)');
+mMax(1, 15);
+console.log('mMax(12, 3)');
+mMax(12, 3);
+console.log('mMax(15, 2)');
+mMax(15, 2);
+console.log('mMax(1, 15)');
+mMax(1, 15);
+console.log('mMax(10, 8)');
+mMax(10, 8);
diff --git a/JavaScript/4-async.js b/JavaScript/4-async.js
@@ -9,7 +9,7 @@ let memoizeAsync = (lib, fnName) => {
   let fn = lib[fnName];
   let cache = {};
   console.log('override ' + fnName);
-  lib[fnName] = function(...args) {
+  lib[fnName] = (...args) => {
     console.dir({call: fnName, args, cache });
     let cb = args.pop();
     let record = cache[args[0]];
@@ -30,9 +30,9 @@ let memoizeAsync = (lib, fnName) => {
 
 memoizeAsync(api.fs, 'readFile');
 
-api.fs.readFile('memoizeAsync.js', (err, data) => {
+api.fs.readFile('4-async.js', (err, data) => {
   console.log('data length: ' + data.length);
-  api.fs.readFile('memoizeAsync.js', (err, data) => {
+  api.fs.readFile('4-async.js', (err, data) => {
     console.log('data length: ' + data.length);
   });
 });
diff --git a/JavaScript/memoize.js b/JavaScript/memoize.js
diff --git a/JavaScript/memoize2.js b/JavaScript/memoize2.js
