HM1

Ala S. Ayaad · Ala S. Ayaad · commit fd34665d4e62 · 2017-12-06T07:54:30.000-08:00
diff --git a/src/arrays.js b/src/arrays.js
@@ -1,37 +1,45 @@
-// Complete the following functions.
-// These functions only need to work with arrays.
-// Do NOT use the built in array methods to solve these. forEach, map, reduce, filter, includes, etc.
-// You CAN use concat, push, pop, etc. but do not use the exact method that you are replicating
-// You can use the functions that you have already written to help solve the other problems
-
 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.
-  // 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) => {
-  // Produces a new array of values by mapping each value in list through a transformation function (iteratee).
-  // Return the new array.
+  const newArray = [];
+  for (let i = 0; i < elements.length; i++) {
+    newArray.push(cb(elements[i]));
+  }
+  return newArray;
 };
 
 const reduce = (elements, cb, startingValue) => {
-  // Combine all elements into a single value going from left to right.
-  // 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.
+  const newElements = elements.slice();
+  if (startingValue === undefined) {
+    startingValue = newElements.shift();
+  }
+  let memo = startingValue;
+  each(newElements, (el) => {
+    memo = cb(memo, el);
+  });
+  return memo;
 };
 
 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.
+  for (let i = 0; i < elements.length; i++) {
+    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
+  const newArr = [];
+  for (let i = 0; i < elements.length; i++) {
+    if (cb(elements[i])) {
+      newArr.push(elements[i]);
+    }
+  }
+  return newArr;
 };
 
 /* STRETCH PROBLEM */
diff --git a/src/callbacks.js b/src/callbacks.js
@@ -1,30 +1,30 @@
-/* eslint-disable */
-
 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.length); // do i have ur code ryan ? ahh
+  cb(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.
+  cb(x + y);
 };
 
 const multiplyNums = (x, y, cb) => {
-  // multiplyNums multiplies two numbers and passes the result to the callback.
+  cb(x * y);
 };
 
 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 cb(true);
+    }
+  }
+  return cb(false);
 };
 
 /* STRETCH PROBLEM */
diff --git a/src/closure.js b/src/closure.js
@@ -1,22 +1,26 @@
 // Complete the following functions.
 
 const counter = () => {
-  // Return a function that when invoked increments and returns a counter variable.
-  // Example: const newCounter = counter();
-  // newCounter(); // 1
-  // newCounter(); // 2
+  let count = 0;
+  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 counts = 0;
+  // return {
+  //   increment: () => ++counts,
+  //   decrement: () => --counts,
 };
 
 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) => {
+    // watch for n. -> "Base Case"
+    if (n === count) return null; // once cb is called n amount of times, return null
+    count++; // else, invoke cb() and increment counter
+    return cb(...args);
+  };
+}; // The returned function should only allow `cb` to be invoked `n` times.
 
 /* STRETCH PROBLEM */
 
diff --git a/src/objects.js b/src/objects.js
@@ -2,15 +2,11 @@
 // Reference http://underscorejs.org/ for examples.
 
 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) => {
@@ -19,8 +15,7 @@ const mapObject = (obj, cb) => {
 };
 
 const pairs = (obj) => {
-  // Convert an object into a list of [key, value] pairs.
-  // http://underscorejs.org/#pairs
+  return Object.entries(obj);
 };
 
 /* STRETCH PROBLEMS */
