From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../reference/global_objects/math/pi/index.html | 115 +++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html (limited to 'files/zh-cn/web/javascript/reference/global_objects/math/pi') diff --git a/files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html b/files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html new file mode 100644 index 0000000000..77f373196e --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/math/pi/index.html @@ -0,0 +1,115 @@ +--- +title: Math.PI +slug: Web/JavaScript/Reference/Global_Objects/Math/PI +translation_of: Web/JavaScript/Reference/Global_Objects/Math/PI +--- +
{{JSRef("Global_Objects", "Math")}}
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概述

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Math.PI 表示一个圆的周长与直径的比例，约为 3.14159：

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Math.PI=π≈3.14159\mathtt{\mi{Math.PI}} = \pi \approx 3.14159

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{{js_property_attributes(0,0,0)}}
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描述

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由于 PI 是 Math 的静态属性，所以应该像这样使用：Math.PI，而不是作为你创建的 Math 实例的属性（Math 不是构造函数）。

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示例

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使用 Math.PI

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下面的函数使用 Math.PI 计算给定半径的圆周长：

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function calculateCircumference (radius) {
+  return 2 * Math.PI * radius;
+}
+
+calculateCircumference(1);  // 6.283185307179586
+ +

规范

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规范版本规范状态注解
ECMAScript 1st Edition. Implemented in JavaScript 1.0StandardInitial definition.
{{SpecName('ES5.1', '#sec-15.8.1.6', 'Math.PI')}}{{Spec2('ES5.1')}} 
{{SpecName('ES6', '#sec-math.pi', 'Math.PI')}}{{Spec2('ES6')}} 
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浏览器兼容性

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{{ CompatibilityTable() }}

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

+ + -- cgit v1.2.3-54-g00ecf