Please tell me what does this map does?

JavaScript
1

Tell us what’s happening:

Your code so far


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

Array.prototype.myMap = function(callback){
var newArray = [];
// Add your code below this line

// Add your code above this line
return newArray;

};

var new_s = s.myMap(function(item){
return item * 2;
});

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36.

Challenge: Implement map on a Prototype

Link to the challenge:
https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype

2

Here is some docs: MDN - Array.prototype.map

Once you understand how map works you can solve the exercise by writing your version of it^^

As you can see a function is passed to myMap method ( in the example it’s this: function(item){ return item * 2; })
What the real map method would do with that function? That’s what you have to write explicitly^^

Good luck! :wink:

1 Like