Math.pow
Math.pow
Math.pow()
函数返回基数(base
)的指数(exponent
)次幂,即baseexponent
。
语法
Math.pow(base, exponent)
参数
base
基数exponent
指数
返回值
代表给定基数的数字,代表给定指数。
描述
由于 pow
是 Math
的静态方法,所以应该像这样使用:Math.pow()
,而不是作为你创建的 Math
对象的方法。
示例
使用Math.pow()
// simple
Math.pow(7, 2 // 49
Math.pow(7, 3 // 343
Math.pow(2, 10 // 1024
// fractional exponents
Math.pow(4, 0.5 // 2 (square root of 4)
Math.pow(8, 1/3 // 2 (cube root of 8)
Math.pow(2, 0.5 // 1.4142135623730951 (square root of 2)
Math.pow(2, 1/3 // 1.2599210498948732 (cube root of 2)
// signed exponents
Math.pow(7, -2 // 0.02040816326530612 (1/49)
Math.pow(8, -1/3 // 0.5
// signed bases
Math.pow(-7, 2 // 49 (squares are positive)
Math.pow(-7, 3 // -343 (cubes can be negative)
Math.pow(-7, 0.5 // NaN (negative numbers don't have a real square root)
// due to "even" and "odd" roots laying close to each other,
// and limits in the floating number precision,
// negative bases with fractional exponents always return NaN
Math.pow(-7, 1/3 // NaN
规范
Specification | Status | Comment |
---|---|---|
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.0. |
ECMAScript 5.1 (ECMA-262)The definition of 'Math.pow' in that specification. | Standard | |
ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'Math.pow' in that specification. | Standard | |
ECMAScript Latest Draft (ECMA-262)The definition of 'Math.pow' in that specification. | Draft | |
浏览器兼容性
Feature | Chrome | Firefox | Edge | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic Support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic Support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |