completed

src/arrays.js

@@ -14,12 +14,20 @@ const each = (elements, cb) => {
   // This only needs to work with arrays.
   // You should also pass the index into `cb` as the second argument
   // based off http://underscorejs.org/#each
+  for (let i = 0; i <= elements.length; i++) {
+    cb(elements[i], i);
+  }
 };
 
 const map = (elements, cb) => {
   // Do NOT use .map, to complete this function.
   // Produces a new array of values by mapping each value in list through a transformation function (iteratee).
   // Return the new array.
+  const newArr = [];
+  for (let i = 0; i < elements.length; i++) {
+    newArr.push(cb(elements[i]));
+  }
+  return newArr;
 };
 
 const reduce = (elements, cb, startingValue) => {
@@ -28,19 +36,48 @@ const reduce = (elements, cb, startingValue) => {
   // Elements will be passed one by one into `cb` along with the `startingValue`.
   // `startingValue` should be the first argument passed to `cb` and the array element should be the second argument.
   // `startingValue` is the starting value.  If `startingValue` is undefined then make `elements[0]` the initial value.
+  let startingIndex = 0;
+  let temp = startingValue;
+  if (startingValue === undefined) {
+    temp = elements[0];
+    startingIndex = 1;
+  }
+  for (let i = startingIndex; i < elements.length; i++) {
+    temp = cb(temp, elements[i]);
+  }
+  return temp;
 };
 
 const find = (elements, cb) => {
   // Do NOT use .includes, to complete this function.
   // 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.
+  for (let i = 0; i < elements.length; i++) {
+    if (cb(elements[i]) === true) {
+      return elements[i];
+    }
+  }
+  return undefined;
 };
 
 const filter = (elements, cb) => {
   // Do NOT use .filter, to complete this function.
   // 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
+  const arr = [];
+  let pass = false;
+  for (let i = 0; i < elements.length; i++) {
+    if (cb(elements[i]) === true) {
+      arr.push(elements[i]);
+      pass = true;
+    }
+  }
+  if (pass === false) {
+    return [];
+  } else if (pass === true) {
+    return arr;
+  }
 };
 
 /* STRETCH PROBLEM */

src/callbacks.js

@@ -1,26 +1,39 @@
 const firstItem = (arr, cb) => {
   // firstItem passes the first item of the given array to the callback function.
+  cb(arr[0]);
 };
 
 const getLength = (arr, cb) => {
   // getLength passes the length of the array into the callback.
+  cb(arr(arr.length));
 };
 
 const last = (arr, cb) => {
   // last passes the last item of the array into the callback.
+  cb(arr[arr.length - 1]);
 };
 
 const sumNums = (x, y, cb) => {
   // sumNums adds two numbers (x, y) and passes the result to the callback.
+  const sum = x + y;
+  cb(sum);
 };
 
 const multiplyNums = (x, y, cb) => {
   // multiplyNums multiplies two numbers and passes the result to the callback.
+  const product = x * y;
+  cb(product);
 };
 
 const contains = (item, list, cb) => {
   // contains checks if an item is present inside of the given array/list.
   // Pass true to the callback if it is, otherwise pass false.
+  for (let i = 0; i <= list.length; i++) {
+    if (list[i] === item) {
+      return true;
+    }
+    cb(item);
+  }
 };
 
 /* STRETCH PROBLEM */

src/closure.js

@@ -5,23 +5,45 @@ const counter = () => {
   // Example: const newCounter = counter();
   // newCounter(); // 1
   // newCounter(); // 2
+  let count = 1;
+  function increment() {
+    return count++;
+  }
+  return increment;
 };
 
 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 count = 0;
+  return {
+    increment() {
+      count++;
+      return count;
+    },
+    decrement() {
+      count--;
+      return count;
+    },
+  };
 };
 
 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 (...args) => {
+    if (count === n) return null;
+    count++;
+    return cb(...args);
+  };
 };
 
 /* STRETCH PROBLEM */
 
 const cacheFunction = (cb) => {
-  // Should return a funciton that invokes `cb`.
+  // Should return a function that invokes `cb`.
   // A cache (object) should be kept in closure scope.
   // The cache should keep track of all arguments have been used to invoke this function.
   // If the returned function is invoked with arguments that it has already seen

src/objects.js

@@ -5,22 +5,32 @@ 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
+  return Object.values(obj);
 };
 
 const mapObject = (obj, cb) => {
   // Like map for arrays, but for objects. Transform the value of each property in turn.
   // http://underscorejs.org/#mapObject
+  const newObj = {};
+  const key = Object.keys(obj);
+  for (let i = 0; i < key.length; i++) {
+    const newValue = cb(obj[key[i]]);
+    newObj[key[i]] = newValue;
+  }
+  return newObj;
 };
 
 const pairs = (obj) => {
   // Convert an object into a list of [key, value] pairs.
   // http://underscorejs.org/#pairs
+  return Object.entries(obj);
 };
 
 /* STRETCH PROBLEMS */

yarn.lock

@@ -1359,14 +1359,10 @@ extglob@^2.0.4:
     snapdragon "^0.8.1"
     to-regex "^3.0.1"
 
-[email protected]:
+[email protected], extsprintf@^1.2.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.3.0.tgz#96918440e3041a7a414f8c52e3c574eb3c3e1e05"
 
-extsprintf@^1.2.0:
-  version "1.4.0"
-  resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.4.0.tgz#e2689f8f356fad62cca65a3a91c5df5f9551692f"
-
 fast-deep-equal@^1.0.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-1.1.0.tgz#c053477817c86b51daa853c81e059b733d023614"
@@ -2440,18 +2436,14 @@ minimatch@^3.0.2, minimatch@^3.0.3, minimatch@^3.0.4:
   dependencies:
     brace-expansion "^1.1.7"
 
-[email protected]:
+[email protected], minimist@~0.0.1:
   version "0.0.8"
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.8.tgz#857fcabfc3397d2625b8228262e86aa7a011b05d"
 
 minimist@^1.1.1:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-1.2.0.tgz#a35008b20f41383eec1fb914f4cd5df79a264284"
 
-minimist@~0.0.1:
-  version "0.0.10"
-  resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.10.tgz#de3f98543dbf96082be48ad1a0c7cda836301dcf"
-
 mixin-deep@^1.2.0:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/mixin-deep/-/mixin-deep-1.3.1.tgz#a49e7268dce1a0d9698e45326c5626df3543d0fe"