adding description

Author: CemWebDev

easy/array-reduce-transformation.js

@@ -1,3 +1,12 @@
+/**
+ * Reduces an array of numbers to a single value using a provided function and initial value.
+ *
+ * @param {number[]} numbers - The array of numbers to reduce.
+ * @param {function} fn - The function to apply to each element and the accumulator. It takes two arguments: the accumulator and the current element.
+ * @param {number} init - The initial value of the accumulator.
+ * @returns {number} - The final reduced value after applying the function to all elements.
+ */
+
 const reduce = (numbers, fn, init) => {
   numbers.forEach((element) => {
     init = fn(init, element);

easy/filter-array.js

@@ -1,3 +1,11 @@
+/**
+ * Filters an array based on a provided function and returns a new array with elements that pass the test.
+ * 
+ * @param {Array} arr - The array of elements to be filtered.
+ * @param {function} fn - The function to test each element. It takes two arguments: the current element and its index. Should return a boolean indicating whether the element should be included in the new array.
+ * @returns {Array} - A new array containing only the elements that passed the test.
+ */
+
 const filter = (arr, fn) => {
   let filteredArr = [];
   arr.forEach((element, index) => {

easy/to-be-or-not-to-be.js

@@ -1,3 +1,12 @@
+/**
+ * Creates an object with methods for testing value equality.
+ *
+ * @param {*} val - The value to be tested.
+ * @returns {object} - An object with two methods:
+ *   - `toBe(expected)`: Checks if `val` is strictly equal to `expected`. Throws an error if they are not equal.
+ *   - `notToBe(expected)`: Checks if `val` is not strictly equal to `expected`. Throws an error if they are equal.
+ */
+
 const expect = (val) => {
   return {
     toBe: (expected) => {

easy/transform-array.js

@@ -1,3 +1,11 @@
+/**
+ * Applies a transformation function to each element in an array and returns a new array with the transformed elements.
+ *
+ * @param {Array} arr - The array of elements to be transformed.
+ * @param {function} fn - The function to apply to each element in the array. It takes two arguments: the current element and its index.
+ * @returns {Array} - A new array containing the results of applying `fn` to each element in `arr`.
+ */
+
 const map = (arr, fn) => {
   let transformedArray = [];
   arr.forEach((item, index) => {