Answer requires "callback" without syntax explanation

Tell us what’s happening:
I am confused.
I was trying to work through this problem without knowing I would
need to use “callback” that was discussed in the previous lesson.
No syntax was provided to explain how to use it nor any examples.

My concern is that I am left with having to memorize this without understanding
how to use “callback”. Thankfully my wife helped me understand “callback” is
a function but I wouldn’t have realized I need to include arguments with “callback”.
My concern is that there is an implied knowledge here for someone who has
used Javascript with years of experience prior to taking this course.

How should I have known to use callback inside the function and
include an argument?

Your code so far

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

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

// Only change 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; rv:81.0) Gecko/20100101 Firefox/81.0.

Challenge: Implement map on a Prototype

Link to the challenge:

This hint is in this sentence:

the map method returns an array of the same length as the one it was called on

Basically, you’ll probably need to google and read MDN docs, w3 schools, Stack Overflow questions, blogs, and even pursue other sources such as books to really understand this stuff. I think of the curriculum here as more of a test or sampling than a fleshed-out, progressive, one-stop-shop curriculum. It will be less frustrating if you accept that you’ll need to do outside work to get through here.

I do understand what you are saying.
The problem I run into is…How can one ask a question if one doesn’t realize there is knowledge they need before they do the current section on Javascript? If the current section doesn’t discuss knowledge needed, how does one know they are missing knowledge? One can’t ask the right question if one does not realize they need to understand a topic or idea because it wasn’t mentioned or discussed.

I think the way it works is–pretty much everyone feels that way (at least I do). For me, I solve that by just trying to become comfortable with not knowing everything. Eventually things start to make sense as more knowledge is gained.

the first time I got stuck (still a freshman here) was at basic algorithm scripting, I had no idea what to do so i just looked at the solutions and didn’t know what was going on, then i began searching stuff on google, the curriculm isn’t bad for learning, when you get stuck on a problem that feels like it has a solution you don’t know just search the question, here you’re asked to implement a map function on your own based on your knowledge about map