Please note, this is a STATIC archive of website developer.mozilla.org from 03 Nov 2016, cach3.com does not collect or store any user information, there is no "phishing" involved.

Number.POSITIVE_INFINITY

概述

Number.POSITIVE_INFINITY 属性表示正无穷大。

不必创建一个 Number 实例,可使用 Number.POSITIVE_INFINITY 来访问该静态属性。

Number.POSITIVE_INFINITY 属性的属性特性:
writable false
enumerable false
configurable false

描述

Number.POSITIVE_INFINITY 的值同全局对象 Infinity 属性的值相同。

该值的表现同数学上的无穷大有点儿不同:

  • 任何正值,包括 POSITIVE_INFINITY,乘以 POSITIVE_INFINITYPOSITIVE_INFINITY
  • 任何负值,包括 NEGATIVE_INFINITY,乘以 POSITIVE_INFINITYNEGATIVE_INFINITY
  • 0 乘以 POSITIVE_INFINITY 为 NaN。
  • NaN 乘以 POSITIVE_INFINITY 为 NaN。
  • POSITIVE_INFINITY 除以 NEGATIVE_INFINITY 以外的任何负值为 NEGATIVE_INFINITY
  • POSITIVE_INFINITY 除以 POSITIVE_INFINITY 以外的任何正值为 POSITIVE_INFINITY
  • POSITIVE_INFINITY 除以 NEGATIVE_INFINITYPOSITIVE_INFINITY 为 NaN。
  • 任何数除以 POSITIVE_INFINITY 为 0。

You might use the Number.POSITIVE_INFINITY property to indicate an error condition that returns a finite number in case of success. Note, however, that isFinite would be more appropriate in such a case.

示例

下例中,赋值给变量 bigNumber 一个大于 JavaScript 中最大值的值。当 if 语句执行时,变量 bigNumber 值为 "Infinity", 因此在继续执行代码前,为变量 bigNumber 设置一个容易管理的值。

var bigNumber = Number.MAX_VALUE * 2
if (bigNumber == Number.POSITIVE_INFINITY) {
 bigNumber = returnFinite();
}

规范

Specification Status Comment
ECMAScript 1st Edition. Implemented in JavaScript 1.1 Standard Initial definition.
ECMAScript 5.1 (ECMA-262)
Number.POSITIVE_INFINITY
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
Number.POSITIVE_INFINITY
Standard  

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)

相关链接

文档标签和贡献者

 此页面的贡献者: helinjiang, AlexChao
 最后编辑者: helinjiang,