概览
圆括号运算符( )
用来控制表达式中的运算优先级.
语法
( )
说明
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 1st Edition. | Standard | Initial definition. Implemented in JavaScript 1.0 |
ECMAScript 5.1 (ECMA-262) The Grouping Operator |
Standard | |
ECMAScript 6 (ECMA-262) The Grouping Operator |
Release Candidate |
浏览器兼容性
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) |