JavaScript Array map()

Return a new array with the square root of all element values:

const numbers = [4, 9, 16, 25];
const newArr = numbers.map(Math.sqrt)

Multiply all the values in an array with 10:

const numbers = [65, 44, 12, 4];
const newArr = numbers.map(myFunction)

function myFunction(num) {
return num * 10;
}

More examples below.

Description

map() creates a new array from calling a function for every array element.

map() does not execute the function for empty elements.

map() does not change the original array.

array.map( function(currentValue, index, arr), thisValue)

Parameter	Description
function()	Required. A function to be run for each array element.
currentValue	Required. The value of the current element.
index	Optional. The index of the current element.
arr	Optional. The array of the current element.
thisValue	Optional. Default value `undefined`. A value passed to the function to be used as its `this` value.