From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../number/negative_infinity/index.html | 112 +++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 files/zh-cn/web/javascript/reference/global_objects/number/negative_infinity/index.html (limited to 'files/zh-cn/web/javascript/reference/global_objects/number/negative_infinity') diff --git a/files/zh-cn/web/javascript/reference/global_objects/number/negative_infinity/index.html b/files/zh-cn/web/javascript/reference/global_objects/number/negative_infinity/index.html new file mode 100644 index 0000000000..6649246cf5 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/number/negative_infinity/index.html @@ -0,0 +1,112 @@ +--- +title: Number.NEGATIVE_INFINITY +slug: Web/JavaScript/Reference/Global_Objects/Number/NEGATIVE_INFINITY +translation_of: Web/JavaScript/Reference/Global_Objects/Number/NEGATIVE_INFINITY +--- +
+ {{JSRef("Global_Objects", "Number")}}
+

概述

+

Number.NEGATIVE_INFINITY 属性表示负无穷大。

+

不用创建一个 {{jsxref("Global_Objects/Number", "Number")}} 实例，使用 Number.NEGATIVE_INFINITY 来访问该静态属性。

+

{{js_property_attributes(0,0,0)}}

+

描述

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Number.NEGATIVE_INFINITY 的值和全局对象的 {{jsxref("Global_Objects/Infinity", "Infinity")}} 属性的负值相同。

+

该值的行为同数学上的无穷大（infinity）有一点儿不同：

+ +

为了成功返回一个有限值，你可能会使用 Number.NEGATIVE_INFINITY 属性来判断是否显示一个条件错误 。然而 {{jsxref("Global_Objects/isFinite", "isFinite")}} 方法更适合这种情况。

+

示例

+

下例中，赋值给变量 smallNumber 一个明显小于 JavaScript 中的最小值的值。当 if 语句执行时，smallNumber 值为 "-Infinity"，因此在继续执行代码前，smallNumber 被设为一个更容易管理的值。

+
var smallNumber = (-Number.MAX_VALUE) * 2
+
+if (smallNumber == Number.NEGATIVE_INFINITY) {
+ smallNumber = returnFinite();
+}
+
+

规范

+ + + + + + + + + + + + + + + + + + + + + + + +
SpecificationStatusComment
ECMAScript 1st Edition. Implemented in JavaScript 1.1StandardInitial definition.
{{SpecName('ES5.1', '#sec-15.7.3.5', 'Number.NEGATIVE_INFINITY')}}{{Spec2('ES5.1')}} 
{{SpecName('ES6', '#sec-number.negative_infinity', 'Number.NEGATIVE_INFINITY')}}{{Spec2('ES6')}} 
+

浏览器规范

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{{ CompatibilityTable() }}

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+ + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}
+
+
+ + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}{{ CompatVersionUnknown() }}
+
+

相关链接

+ -- cgit v1.2.3-54-g00ecf