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JavaScript Array map()

Example 1

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

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

Definition and Usage

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

map() calls a function once for each element in an array.

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

map() does not change the original array.

Example 2

Multiply all the values in array with 10:

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

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

Get the full name for each person:

const persons = [
  {firstname : "Malcom", lastname: "Reynolds"},
  {firstname : "Kaylee", lastname: "Frye"},
  {firstname : "Jayne", lastname: "Cobb"}
];

persons.map(getFullName);

function getFullName(item) {
  return [item.firstname,item.lastname].join(" ");
}
Try it Yourself »

Browser Support

map() is an ES5 feature (JavaScript 2009). It is fully supported in all modern browsers:

Chrome IE Edge Firefox Safari Opera
Yes 9.0 Yes Yes Yes Yes


Syntax

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

Parameters

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.

Return Value

An Array.

The results of a function for each array element.