Number.parseFloat() - JavaScript 编辑

The 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.

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.

Syntax

Number.parseFloat(string)

Parameters

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.

Return value

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;
}

Examples

Number.parseFloat vs parseFloat

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

Number.parseFloat === parseFloat; // true

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

See parseFloat() for more detail and examples.

Specifications

Specification
ECMAScript (ECMA-262) The definition of 'Number.parseFloat' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• Number

  The object this method belongs to.

• The global parseFloat() method.