Infinity
全局属性 Infinity
是一个数值,表示无穷大。
| Property attributes of Infinity |
|:----|
| Writable | no |
| Enumerable | no |
| Configurable | no |
语法
Infinity
描述
Infinity 是全局对象(global object)的一个属性,即它是一个全局变量。
Infinity 的初始值是 Number.POSITIVE_INFINITY。Infinity(正无穷大)大于任何值。该值和数学意义上的无穷大很像,例如任何正值乘以 Infinity 为 Infinity, 任何数值(除了Infinity 和 -Infinity)除以 Infinity 为 0。
在 ECMAScript 5 的规范中, Infinity 是只读的(实现于 JavaScript 1.8.5 / Firefox 4)。
示例
console.log(Infinity ); /* Infinity */
console.log(Infinity + 1 ); /* Infinity */
console.log(Math.pow(10, 1000)); /* Infinity */
console.log(Math.log(0) ); /* -Infinity */
console.log(1 / Infinity ); /* 0 */
规范
Specification | Status | Comment |
---|---|---|
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.3 |
ECMAScript 5.1 (ECMA-262)The definition of 'Infinity' in that specification. | Standard | |
ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'Infinity' in that specification. | Standard | |
ECMAScript Latest Draft (ECMA-262)The definition of 'Infinity' in that specification. | Draft | |
浏览器兼容性
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
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