Implementation of Map and Filter Array function in JavaScript

jsbin.tijapit.js

Array.prototype.myMap = function(fn) {
  let newArray = [];
  
  this.forEach(item => {
    newArray.push(fn(item));
  })
  
  return newArray;
}

Array.prototype.myFilter = function(fn) {
  let newArray = [];
  
  this.forEach(item => {
    if (fn(item)) 
      newArray.push(item);
  })
  
  return newArray;
}


let map = [1, 2, 3, 4, 5];
const sqrt = (a) => a * a;
const gt2 = (a) => a > 2;

console.log(map.myMap(sqrt));
console.log(map.myFilter(gt2));