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Math.sqrt()

概述

Math.sqrt() 函数返回一个数的平方根,即:

x0,Math.sqrt(x)=x=the uniquey0such thaty2=x\forall x \geq 0, \mathtt{Math.sqrt(x)} = \sqrt{x} = \text{the unique} \; y \geq 0 \; \text{such that} \; y^2 = x

语法

Math.sqrt(x) 

参数

x
一个数值

描述

如果参数 number 为负值,则 sqrt 返回 NaN

由于 sqrt 是 Math 的静态方法,所以应该像这样使用:Math.sqrt(),而不是作为你创建的 Math 实例的方法。

示例

例子:使用 Math.sqrt

Math.sqrt(9); // 3
Math.sqrt(2); // 1.414213562373095

Math.sqrt(1);  // 1
Math.sqrt(0);  // 0
Math.sqrt(-1); // NaN

规范

规范版本 规范状态 注解
ECMAScript 1st Edition. Implemented in JavaScript 1.0 Standard Initial definition.
ECMAScript 5.1 (ECMA-262)
Math.sqrt
Standard  
ECMAScript 6 (ECMA-262)
Math.sqrt
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)

 

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