freeCodeCamp Challenge Guide: Implement the filter Method on a Prototype

Guide
1

Implement the filter Method on a Prototype

Solutions

Solution 1 (Click to Show/Hide) 
Array.prototype.myFilter = function(callback) {
  const newArray = [];
  // Only change code below this line
  for (let i = 0; i < this.length; i++) {
    if (Boolean(callback(this[i], i, this)) === true) {
      newArray.push(this[i]);
    }
  }
  // Only change code above this line
  return newArray;
};
Solution 2 (Click to Show/Hide) 
Array.prototype.myFilter = function (callback) {
  const newArray = [];
  // Only change code below this line
  for (let i = 0; i < this.length; i++) {
    if (callback(this[i], i, this) == true) {
      newArray.push(this[i]);
    }
  }
  // Only change code above this line
  return newArray;
};
Solution 3 (Click to Show/Hide) 
Array.prototype.myFilter = function (callback) {
  const newArray = [];
  // Only change code below this line
  for (const [index, elem] of this.entries()) {
    if (callback(elem, index, this)) newArray.push(elem);
  }
  // Only change code above this line
  return newArray;
};

Relevant Links

MDN: this keyword

Gentle Explanation of “this” in JavaScript

MDN: Details of the object model

MDN: Inheritance and the prototype chain

MDN: Array.prototype.entries()

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