在此页

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

Number.parseFloat() method parses an argument and returns a floating point number. If a number cannot be parsed from the argument, it returns NaN .

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.

句法

Number.parseFloat(string)
					

参数

string

The value to parse. If this argument is not a string, then it is converted to one using the ToString abstract operation. Leading whitespace in this argument is ignored.

返回值

A floating point number parsed from the given string .

Or NaN when the first non-whitespace character cannot be converted to a number.

Polyfill

if (Number.parseFloat === undefined) {
  Number.parseFloat = parseFloat;
}
					

范例

Number.parseFloat vs parseFloat

This method has the same functionality as the global parseFloat() 函数：

Number.parseFloat === parseFloat; // true
					

This method is also part of ECMAScript 2015. (Its purpose is modularization of globals.)

见 parseFloat() for more detail and examples.

规范

规范
ECMAScript (ECMA-262) The definition of 'Number.parseFloat' 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
parseFloat	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

  The object this method belongs to.

• 全局 parseFloat() 方法。

元数据

• 最后修改： Jul 1, 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()