圆括号运算符( )
用来控制表达式中的运算优先级。
这些交互的事例资源都是基于Github的仓库.如果你想提交更多的交互事例,请克隆这个urlhttps://github.com/mdn/interactive-examples 并且向我们发送合并请求
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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.
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
Specification | Status | Comment |
---|---|---|
ECMAScript Latest Draft (ECMA-262) The Grouping Operator |
Draft | |
ECMAScript 2015 (6th Edition, ECMA-262) The Grouping Operator |
Standard | |
ECMAScript 5.1 (ECMA-262) The Grouping Operator |
Standard | |
ECMAScript 1st Edition (ECMA-262) The Grouping Operator |
Standard | 初始化定义.在JavaScript1.0中生效 |
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Grouping operator () | Chrome Full support Yes | Edge Full support Yes | Firefox Full support 1 | IE Full support Yes | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support 4 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes | nodejs Full support Yes |