@simulstop I can't tell if you're asking, but if so (or in case someone wanted to know).

The short version is, take an array, pass each element of the array one at a time, through the function provided (the callback), and return a new array where each element in the new array is the result of the callback.

for example:

let lower = ['a', 'b', 'c']
let upper = lower.map(letter => letter.toUpperCase())
console.log(upper) //['A', 'B', 'C']

It's just a cleaner way of creating a new array by transforming or returning properties from an existing array. The code below does the same thing as the .map() above, but with some extra lines of code

let lower = ['a', 'b', 'c']
let upper = []
for (letter of lower) {
    upper.push(letter.toUpperCase())
}
console.log(upper) //['A', 'B', 'C']

It's All So Easy