Math.PI
Math.PI?表示一个圆的周长与直径的比例，约为 3.14159：
Math.PI=π≈3.14159\mathtt{\mi{Math.PI}} = \pi \approx 3.14159
| Math.PI属性的属性特性 |
|:----|
| Writable | no |
| Enumerable | no |
| Configurable | no |
描述
由于PI是Math?的静态属性，所以应该像这样使用：Math.PI，而不是作为你创建的?Math实例的属性（Math?不是构造函数）。
示例
使用Math.PI
下面的函数使用 Math.PI 计算给定半径的圆周长：
function calculateCircumference(radius) {
return Math.PI * (radius + radius);
}
calculateCircumference(1); // 6.283185307179586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.PI' in that specification. | Standard | ? |
ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'Math.PI' in that specification. | Standard | ? |
ECMAScript Latest Draft (ECMA-262)The definition of 'Math.PI' in that specification. | Living Standard | ? |
浏览器兼容性
Feature | Chrome | Edge | Firefox | 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) |
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