The concat()
method combines the text of one or more strings and returns a new string.
Syntax
str.concat(string2[, string3, ..., stringN])
Parameters
string2...stringN
- Strings to concatenate to this string.
Return value
A new string containing the combined text of the strings provided.
Description
The concat()
function combines the text from one or more strings and returns a new string. Changes to the text in one string do not affect the other string.
Examples
Using concat()
The following example combines strings into a new string.
var hello = 'Hello, '; console.log(hello.concat('Kevin', '. Have a nice day.')); /* Hello, Kevin. Have a nice day. */ var greetList = ['Hello', ' ', 'Venkat', '!']; "".concat(...greetList); // "Hello Venkat!" "".concat({}); // [object Object] "".concat([]); /// "" "".concat(null); // "null" "".concat(true); // "true" "".concat(4, 5); // "45" "".concat({}); // [object Object]
Performance
It is strongly recommended that assignment operators (+
, +=
) are used instead of the concat()
method. See this performance test.
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.2. |
ECMAScript 5.1 (ECMA-262) The definition of 'String.prototype.concat' in that specification. |
Standard | |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'String.prototype.concat' in that specification. |
Standard | |
ECMAScript Latest Draft (ECMA-262) The definition of 'String.prototype.concat' in that specification. |
Living Standard |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | Yes | Yes | Yes | Yes | Yes | Yes |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic support | Yes | Yes | Yes | Yes | Yes | Yes | Yes |