Saw the answer, still don't understand :(

JavaScript
1

Tell us what’s happening:
I don’t understand the answer. Could anyone help me?

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
  this.forEach(a => newArray.push(callback(a)));
  // Add your code above this line
  return newArray;

};

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

It’s much easier to help you if we can see the code that you wrote when you were trying to solve the problem.

3 
// the global Array
var s = [23, 65, 98, 5];

Array.prototype.myMap = function(callback){
  var newArray = [];
  // Add your code below this line
  for(let i=0;i<s.length;i++)
  {
    newArray.push(callback);
  }
  // Add your code above this line
  return newArray;

};

var new_s = s.myMap(function(item){
  return item * 2;
});
4

Give me the link to the challenge please.

It might be failing because you are missing:

this.forEach(a => newArray.push(callback(a)))

But idk as long as I don’t read the challenges.

5

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make easier to read.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.

Note: Backticks are not single quotes.

markdown_Forums

1 Like
6

It looks like you were probably most of the way there, but forgot to call callback with an argument.

1 Like
7

Yes,but I don’t understand that, callback is an argument itself, why it used as a function?

8

The callback is a function. In JavaScript, functions are “first class citizens”. This means that they can be passed into a function as an argument (this is how callbacks work) or returned by functions. You’ve actually done exercises related to both of these cases, earlier in the JavaScript curriculum.

9

Thanks for your help.