非常教程

JavaScript参考手册

Operators

Grouping

圆括号运算符( ) 用来控制表达式中的运算优先级.

语法

 ( )

描述

圆括号运算符由一对圆括号组成,包裹表达式和子表达式用来覆盖常规的 运算符优先级 ,达到低优先级的表达式比高优先级的表达式更早运算.

示例

下面的代码展示了加法运算先于乘法运算的情况.

var a = 1;
var b = 2;
var c = 3;

// default precedence
a + b * c     // 7
// evaluated by default like this
a + (b * c)   // 7

// now overriding precedence 
// addition before multiplication   
(a + b) * c   // 9

// which is equivalent to
a * c + b * c // 9

规范

Specification

Status

Comment

ECMAScript Latest Draft (ECMA-262)The definition of 'The Grouping Operator' in that specification.

Living Standard

ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'The Grouping Operator' in that specification.

Standard

ECMAScript 5.1 (ECMA-262)The definition of 'The Grouping Operator' in that specification.

Standard

ECMAScript 1st Edition (ECMA-262)The definition of 'The Grouping Operator' in that specification.

Standard

Initial definition. Implemented in JavaScript 1.0.

浏览器兼容性

Feature

Chrome

Edge

Firefox (Gecko)

Internet Explorer

Opera

Safari

Basic support

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

Feature

Android

Chrome for Android

Edge

Firefox Mobile (Gecko)

IE Mobile

Opera Mobile

Safari Mobile

Basic support

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

JavaScript

JavaScript 是一种高级编程语言,通过解释执行,是一门动态类型,面向对象(基于原型)的解释型语言。它已经由ECMA(欧洲电脑制造商协会)通过 ECMAScript 实现语言的标准化。它被世界上的绝大多数网站所使用,也被世界主流浏览器( Chrome、IE、FireFox、Safari、Opera )支持。JavaScript 是一门基于原型、函数先行的语言,是一门多范式的语言,它支持面向对象编程,命令式编程,以及函数式编程。它提供语法来操控文本、数组、日期以及正则表达式等,不支持 I/O,比如网络