`concat()` 方法将一个或多个字符串与原字符串连接合并，形成一个新的字符串并返回。

## 语法

    str.concat(string2, string3[, ..., stringN])

### 参数

`string2...stringN`
  和原字符串连接的多个字符串

## 描述

`concat` 方法将一个或多个字符串与原字符串连接合并，形成一个新的字符串并返回。 `concat` 方法并不影响原字符串。

## 示例

### 例子：使用 `concat`

下面的例子演示如何将多个字符串与原字符串合并为一个新字符串

    var hello = "Hello, ";
    console.log(hello.concat("Kevin", " have a nice day.")); /* Hello, Kevin have a nice day. */

## 性能

强烈建议使用 赋值操作符（+, +=）代替 `concat` 方法。参看 性能测试（perfomance test）。

## 规范

Specification | Status | Comment
--- | --- | ---
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.2.
ECMAScript 5.1 (ECMA-262) String.prototype.concat | Standard |
ECMAScript 2015 (6th Edition, ECMA-262) String.prototype.concat | Standard |

## 浏览器兼容性

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

- Desktop
- Mobile

Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari
--- | --- | --- | --- | --- | ---
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes)

Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile
--- | --- | --- | --- | --- | --- | ---
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes)

## 相关链接

- `Array.prototype.concat()`
- Assignment operators