bluebackground · Sep 8, 2017 · Sep 8, 2017 · Sep 9, 2017 · Sep 11, 2017 · ryan-hamblin
diff --git a/src/arrays.js b/src/arrays.js
@@ -8,36 +8,111 @@ const each = (elements, cb) => {
   // Iterates over a list of elements, yielding each in turn to the `cb` function.
   // This only needs to work with arrays.
   // based off http://underscorejs.org/#each
+
+  for (let i = 0; i < elements.length; i++) {
+    cb(elements[i], i);
+  }
 };
 
 const map = (elements, cb) => {
   // Produces a new array of values by mapping each value in list through a transformation function (iteratee).
   // Return the new array.
+
+  // declare result array object to be returned.
+  const result = [];
+  // loop over the elements
+  for (let i = 0; i < elements.length; i++) {
+    // invoke cb function on elements
+    result.push(cb(elements[i]));
+    // push result to result array
+  }
+  // return result array
+  return result;
 };
 
 const reduce = (elements, cb, memo = elements.shift()) => {
   // Combine all elements into a single value going from left to right.
   // Elements will be passed one by one into `cb`.
   // `memo` is the starting value.  If `memo` is undefined then make `elements[0]` the initial value.
+
+  // cb(memo, elements[0]);
+  let result = memo;
+  // const initialValue = memo;
+
+  if (elements.length > 1) {
+    // Loop over the array
+    for (let i = 0; i < elements.length; i++) {
+      // call the cb function on current element in elements.
+      result = cb(result, elements[i]);
+      // call shift on elements
+      // save returned value to memo.
+      // memo = result;
+    }
+  }
+  return result;
 };
 
 const find = (elements, cb) => {
   // Look through each value in `elements` and pass each element to `cb`.
   // If `cb` returns `true` then return that element.
   // Return `undefined` if no elements pass the truth test.
+
+  // Loop through elements array.
+  for (let i = 0; i < elements.length; i++) {
+    // Check truth statement of the callback.
+    // Return the value when the callback is true.
+    if (cb(elements[i])) {
+      return elements[i];
+    }
+  }
 };
 
 const filter = (elements, cb) => {
   // Similar to `find` but you will return an array of all elements that passed the truth test
   // Return an empty array if no elements pass the truth test
+  // Create a result array that stores all the values that will be returned.
+
+  const result = [];
+  // Loop Through the elements array.
+  for (let i = 0; i < elements.length; i++) {
+    // Push elements that pass the test to the result array.
+    if (cb(elements[i])) {
+      result.push(elements[i]);
+    }
+  }
+  // Return the result array.
+  return result;
 };
 
 /* Extra Credit */
 const flatten = (elements) => {
   // Flattens a nested array (the nesting can be to any depth).
   // Example: flatten([1, [2], [3, [[4]]]]); => [1, 2, 3, 4];
-};
+  let result = [];
+
+  function getValues(element, res = []) {
+      // loop over all elements in array
+    for (let i = 0; i < element.length; i++) {
+      if (typeof element[i] === 'object') {
+        res = getValues(element[i], result);
+      } else {
+        res.push(element[i]);
+      }
+    }
+    return res;
+  }
 
+  for (let i = 0; i < elements.length; i++) {
+    if (typeof elements[i] === 'object') {
+      result = getValues(elements[i], result);
+    } else {
+      result.push(elements[i]);
+    }
+  }
+
+  // result = elements.map(getValues);
+  return result;
+};
 /* eslint-enable no-unused-vars, max-len */
 
 module.exports = {

diff --git a/src/class.js b/src/class.js
@@ -19,6 +19,38 @@
 // `meow` that should return the string `<name> meowed!` where `<name>` is the `name`
 // property set on the Cat instance.
 
+class User {
+  constructor(options) {
+    this.email = options.email;
+    this.password = options.password;
+  }
+
+  comparePasswords(password) {
+    return (password === this.password);
+  }
+}
+
+class Animal {
+  constructor(options) {
+    this.age = options.age;
+  }
+
+  growOlder() {
+    this.age++;
+    return this.age;
+  }
+}
+
+class Cat extends Animal {
+  constructor(options) {
+    super(options);
+    this.name = options.name;
+  }
+
+  meow() {
+    return `${this.name} meowed!`;
+  }
+}
 
 module.exports = {
   User,

diff --git a/src/closure.js b/src/closure.js
@@ -5,17 +5,45 @@ const counter = () => {
   // Example: const newCounter = counter();
   // newCounter(); // 1
   // newCounter(); // 2
+  let count = 0;
+  return () => {
+    count++;
+    return count;
+  };
 };
 
 const counterFactory = () => {
   // Return an object that has two methods called `increment` and `decrement`.
   // `increment` should increment a counter variable in closure scope and return it.
   // `decrement` should decrement the counter variable and return it.
+  let counter1 = 0;
+
+  return {
+    increment: () => {
+      counter1++;
+      return counter1;
+    },
+    decrement: () => {
+      counter1--;
+      return counter1;
+    }
+  };
 };
 
 const limitFunctionCallCount = (cb, n) => {
   // Should return a function that invokes `cb`.
   // The returned function should only allow `cb` to be invoked `n` times.
+  let count = 0;
+
+  return (...val) => {
+    count++;
+
+    if (count < n) {
+      return cb(...val);
+    }
+
+    return null;
+  };
 };
 
 /* Extra Credit */
@@ -26,6 +54,19 @@ const cacheFunction = (cb) => {
   // If the returned function is invoked with arguments that it has already seen
   // then it should return the cached result and not invoke `cb` again.
   // `cb` should only ever be invoked once for a given set of arguments.
+  const arg = [];
+  const result = [];
+  return (unknown) => {
+    if (arg.indexOf(unknown) !== -1) {
+      return result[arg.indexOf(unknown)];
+    }
+    const current = cb(unknown);
+
+    arg.push(unknown);
+    result.push(current);
+
+    return current;
+  };
 };
 
 /* eslint-enable no-unused-vars */

diff --git a/src/es6.js b/src/es6.js
@@ -7,49 +7,47 @@
 //----------------
 // const, =>, default parameters, arrow functions default return statements using ()
 
-var food = 'pineapple';
+const food = 'pineapple';
 
-var isMyFavoriteFood = function(food) {
-  food = food || 'thousand-year-old egg'; //This sets a default value if `food` is falsey
+function isMyFavoriteFood(food = 'thousand-year-old egg') {
   return food === 'thousand-year-old egg';
-};
+}
 
-var isThisMyFavorite = isMyFavoriteFood(food);
+const isThisMyFavorite = isMyFavoriteFood(food);
 
 //----------------
 //const, class, template literals, enhanced object literals (foo: foo, -> foo,)
 
-var User = function(options) {
-  this.username = options.username;
-  this.password = options.password;
-  this.sayHi = function() {
-    return this.username + ' says hello!';
-  };
-}
+class User {
+  constructor(options){
+    this.username = options.username;
+    this.password = options.password;
+  }
 
-var username = 'JavaScriptForever';
-var password = 'password';
+  sayHi(){
+    return `${this.username} says hello!`;
+  }
+}
 
-var me = new User({
+const me = new User({
   username: username,
   password: password,
 });
 
 // ----------------
 // let, const, =>, ... (spread operator)
 
-var addArgs = function () {
-  var sum = 0;
-  for (var i = 0; i < arguments.length; i++) {
-    sum += arguments[i];
+function addArgs() {
+  let sum = 0;
+  for(let arument of arguments){
+    sum+=argument;
   }
   return sum;
-};
+}
 
-var argsToCb = function (cb) {
-  var args = Array.prototype.slice.call(arguments);
-  return cb.apply(null, args.splice(1));
-};
+function argsToCb(cb, ...args) {
+  return cb.apply(null, ...args);
+}
 
 var result = argsToCb(addArgs, 1, 2, 3, 4, 5); //result should be 15
 

diff --git a/src/objects.js b/src/objects.js
@@ -5,34 +5,94 @@ const keys = (obj) => {
   // Retrieve all the names of the object's properties.
   // Return the keys as strings in an array.
   // Based on http://underscorejs.org/#keys
+  return Object.keys(obj);
 };
 
 const values = (obj) => {
   // Return all of the values of the object's own properties.
   // Ignore functions
-  // http://underscorejs.org/#values
+  // http://underscorejs.org/#
+
+  const objKeys = Object.keys(obj);
+  const result = [];
+
+  objKeys.forEach((k) => {
+    return result.push(obj[k]);
+  });
+
+  // for (const key in obj) {
+  //   if (Object.prototype.hasOwnProperty.call(obj, key)) {
+  //     result.push(obj[key]);
+  //   }
+  // }
+  return result;
 };
 
 const mapObject = (obj, cb) => {
   // Like map for arrays, but for objects. Transform the value of each property in turn.
   // http://underscorejs.org/#mapObject
+  const objKeys = Object.keys(obj);
+  const returnObj = Object.assign({}, obj);
+
+  objKeys.forEach((k) => {
+    returnObj[k] = cb(obj[k]);
+  });
+
+  return returnObj;
 };
 
 const pairs = (obj) => {
   // Convert an object into a list of [key, value] pairs.
   // http://underscorejs.org/#pairs
+
+  const objKeys = Object.keys(obj);
+  const result = [];
+
+  objKeys.forEach((k) => {
+    result.push([k, obj[k]]);
+  });
+
+  return result;
 };
 
 const invert = (obj) => {
   // Returns a copy of the object where the keys have become the values and the values the keys.
   // Assume that all of the object's values will be unique and string serializable.
   // http://underscorejs.org/#invert
+  const objKeys = Object.keys(obj);
+  const returnObj = {};
+
+  objKeys.forEach((k) => {
+    returnObj[obj[k]] = k;
+  });
+
+  return returnObj;
 };
 
 const defaults = (obj, defaultProps) => {
   // Fill in undefined properties that match properties on the `defaultProps` parameter object.
   // Return `obj`.
   // http://underscorejs.org/#defaults
+  function hasKey(o, ky) {
+    // const objKeys = Object.keys(o);
+    // return objKeys.includes(ky) || o[ky] !== undefined;
+    return o[ky] === undefined;
+  }
+
+  const defaultKeys = Object.keys(defaultProps);
+
+  defaultKeys.forEach((k) => {
+    if (hasKey(obj, k)) {
+      obj[k] = defaultProps[k];
+    }
+  });
+
+  // for (const key in objKeys) {
+  //   if (obj[key] === undefined && defaultProps.hasKey(key)) {
+  //     obj[key] = defaultProps[key];
+  //   }
+  // }
+  return obj;
 };
 
 /* eslint-enable no-unused-vars */