mdn .map() code example
Example 1: js map constructor
let myMap = new Map([
[1, 'one'], // [key, value]
[2, 'two'],
[3, 'three'],
]) // from MDN
Example 2: array mdn map
let new_array = arr.map(function callback( currentValue[, index[, array]]) {
// return element for new_array
}[, thisArg])
Example 3: javascript map
array.map( item => item.id )
array2.map( item => item.toString() )
array2.map( item => item * 3 )
// this will apply a transformation to all elements of an array
// "" item => something "" is the transformation (function)