Number.parseFloat()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

Number.parseFloat() 静态方法解析参数并返回浮点数。如果无法从参数中解析出一个数字,则返回 NaN

尝试一下

function circumference(r) {
  if (Number.isNaN(Number.parseFloat(r))) {
    return 0;
  }
  return parseFloat(r) * 2.0 * Math.PI;
}

console.log(circumference("4.567abcdefgh"));
// Expected output: 28.695307297889173

console.log(circumference("abcdefgh"));
// Expected output: 0

语法

js
Number.parseFloat(string)

参数

string

要解析的值,会被强制转换为字符串。该参数开头的空白会被忽略。

返回值

由给定 string 解析得到的浮点数。

如果第一个非空白字符不能被转换为数字,则返回 NaN

示例

Number.parseFloat 与 parseFloat 对比

此方法与全局函数 parseFloat() 具有相同的功能:

js
Number.parseFloat === parseFloat; // true

其目的是全局的模块化。

有关更多详细信息和示例,请参见 parseFloat()

规范

Specification
ECMAScript® 2025 Language Specification
# sec-number.parsefloat

浏览器兼容性

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
parseFloat

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Full support
Full support

参见