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  

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