在此页

• 描述
• Polyfill
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

Number.EPSILON property represents the difference between 1 and the smallest floating point number greater than 1.

You do not have to create a Number object to access this static property (use Number.EPSILON ).

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

特性属性在 Number.EPSILON
可写	no
可枚举	no
可配置	no

描述

EPSILON property has a value of approximately 2.2204460492503130808472633361816E-16 ，或 2 -52 .

Polyfill

if (Number.EPSILON === undefined) {
    Number.EPSILON = Math.pow(2, -52);
}
					

范例

Testing equality

x = 0.2;
y = 0.3;
z = 0.1;
equal = (Math.abs(x - y + z) < Number.EPSILON);
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Number.EPSILON' in that specification.

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
EPSILON	Chrome 34	Edge 12	Firefox 25	IE No	Opera 21	Safari 9	WebView Android ≤37	Chrome Android 34	Firefox Android 25	Opera Android 21	Safari iOS 9	Samsung Internet Android 2.0	nodejs 0.12

图例

完整支持

完整支持

不支持

不支持

另请参阅

• Number object it belongs to.

元数据

• 最后修改： May 20, 2020

相关话题

1. 标准内置对象
2. Number
3. 特性
   1. Number.EPSILON
   2. Number.MAX_SAFE_INTEGER
   3. Number.MAX_VALUE
   4. Number.MIN_SAFE_INTEGER
   5. Number.MIN_VALUE
   6. Number.NEGATIVE_INFINITY
   7. Number.NaN
   8. Number.POSITIVE_INFINITY
4. 方法
   1. Number.isFinite()
   2. Number.isInteger()
   3. Number.isNaN()
   4. Number.isSafeInteger()
   5. Number.parseFloat()
   6. Number.parseInt()
   7. Number.prototype.toExponential()
   8. Number.prototype.toFixed()
   9. Number.prototype.toLocaleString()
   10. Number.prototype.toPrecision()
   11. Number.prototype.toSource()
   12. Number.prototype.toString()
   13. Number.prototype.valueOf()
5. 继承：
6. Function
7. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
8. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
9. Object
10. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
11. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()