Functional Programming: Implement the filter Method on a Prototype

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Functional Programming: Implement the filter Method on a Prototype

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It would teach us a lot about the filter method if we try to implement a version of it that behaves exactly like Array.prototype.filter(). It can use either a for loop or Array.prototype.forEach().

Note: A pure function is allowed to alter local variables defined within its scope, although, it's preferable to avoid that as well.

Write your own Array.prototype.myFilter(), which should behave exactly like Array.prototype.filter(). You may use a for loop or the Array.prototype.forEach() method.

script.js

// the global Array
var s = [23, 65, 98, 5];

Array.prototype.myFilter = function(callback){
  var newArray = [];
  for(let i =0; i < this.length ; i++){
    if(callback(this[i])){
      newArray.push(this[i]);
    }
  }
  return newArray;

};

var new_s = s.myFilter(function(item){
  return item % 2 === 1;
});

Much cleaner code => Functional Programming: Implement the filter Method on a Prototype

// The global variable
const s = [23, 65, 98, 5];

Array.prototype.myFilter = function(callback) {
  // Only change code below this line
  const newArray = [];
  s.forEach((num)=>{if(callback(num))newArray.push(num)})
  // Only change code above this line
  return newArray;
};

const new_s = s.myFilter(function(item) {
  return item % 2 === 1;
});
console.log(new_s);

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)){
newArray.push(this[i])
}
}
// Only change code above this line
return newArray;
};

[23, 65, 98, 5, 13].myFilter(item => item % 2) should equal [23, 65, 5, 13].

["naomi", "quincy", "camperbot"].myFilter(element => element === "naomi") should return ["naomi"].

[1, 1, 2, 5, 2].myFilter((element, index, array) => array.indexOf(element) === index) should return [1, 2, 5].