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 |
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:
POSITIVE_INFINITY
,乘以 POSITIVE_INFINITY
为 POSITIVE_INFINITY
。NEGATIVE_INFINITY
,乘以 POSITIVE_INFINITY
为 NEGATIVE_INFINITY
。POSITIVE_INFINITY
为 NaN。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_INFINITY
或 POSITIVE_INFINITY
为 NaN。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.
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();
}
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 |
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) |