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JavaScript Array map() Method

❮ JavaScript Array Reference

Example

Return an array with the square root of all the values in the original array:

var numbers = [4, 9, 16, 25];

function myFunction() {
    x = document.getElementById("demo")
    x.innerHTML = numbers.map(Math.sqrt);
}
Try it Yourself »

More "Try it Yourself" examples below.


Definition and Usage

The map() method creates a new array with the results of calling a function for every array element.

The map() method calls the provided function once for each element in an array, in order.

Note: map() does not execute the function for array elements without values.

Note: map() does not change the original array.


Browser Support

The numbers in the table specify the first browser version that fully supports the method.

Method
map() Yes 9.0 1.5 Yes Yes

Syntax

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

Parameter Values

Parameter Description
function(currentValue, index, arr) Required. A function to be run for each element in the array.
Function arguments:
Argument Description
currentValue Required. The value of the current element
index Optional. The array index of the current element
arr Optional. The array object the current element belongs to
thisValue Optional. A value to be passed to the function to be used as its "this" value.
If this parameter is empty, the value "undefined" will be passed as its "this" value


Technical Details

Return Value: An Array containing the results of calling the provided function for each element in the original array.
JavaScript Version: ECMAScript 3

More Examples

Example

Multiply all the values in array with a specific number:

var numbers = [65, 44, 12, 4];

function multiplyArrayElement(num) {
    return num * document.getElementById("multiplyWith").value;
}

function myFunction() {
    document.getElementById("demo").innerHTML = numbers.map(multiplyArrayElement);
}
Try it Yourself »

Example

Get the full name for each person in the array:

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


function getFullName(item, index) {
    var fullname = [item.firstname,item.lastname].join(" ");
    return fullname;
}

function myFunction() {
    document.getElementById("demo").innerHTML = persons.map(getFullName);
}
Try it Yourself »

❮ JavaScript Array Reference