let arr = ["apple","orange","banana"];
arr.(v => v.toUpperCase());
Original Arrayapple0orange1banana2OutputAPPLE0ORANGE1banana2mapv => v.toUpperCase()

Creates a new array populated with the results of calling the provided function on every element.

map returns a new array.

In most cases, the map method will just take a callback function as an argument.

The callback function can take 3 parameters:
(1) the value of the current element
(2) the index of the current element
(3) the array the map method was called on