The join() method joins all elements of an array into a string.

Syntax

str = arr.join([separator = ','])

Parameters

separator
Optional. Specifies a string to separate each element of the array. The separator is converted to a string if necessary. If omitted, the array elements are separated with a comma. If separator is an empty string, all elements are joined without any characters in between them.

Description

The string conversions of all array elements are joined into one string. If one element is undefined or null, it is converted to the empty string.

Examples

Joining an array four different ways

The following example creates an array, a, with three elements, then joins the array four times: using the default separator, then a comma and a space, then a plus and an empty string.

var a = ['Wind', 'Rain', 'Fire'];
var myVar1 = a.join();      // assigns 'Wind,Rain,Fire' to myVar1
var myVar2 = a.join(', ');  // assigns 'Wind, Rain, Fire' to myVar2
var myVar3 = a.join(' + '); // assigns 'Wind + Rain + Fire' to myVar3
var myVar4 = a.join('');    // assigns 'WindRainFire' to myVar4

Specifications

Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.1.
ECMAScript 5.1 (ECMA-262)
The definition of 'Array.prototype.join' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Array.prototype.join' in that specification.
Standard  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 1.0 1.0 (1.7 or earlier) 5.5 (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

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