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The parseFloat() function parses an argument (converting it to a string first if needed) and returns a floating point number.

Syntax

parseFloat(string)

Parameters

string
The value you want to parse.

Return value

A floating point number parsed from the given argument. If a number cannot be parsed from the argument, instead returns NaN.

Description

parseFloat is a top-level function and not a method of any object.

  • If parseFloat encounters a character other than a plus sign (+), minus sign (- U+002D HYPHEN-MINUS), numeral (09), decimal point (.), or exponent (e or E), it returns the value up to that character, ignoring the invalid character and characters following it.
  • A second decimal point also stops parsing (characters up to that point will still be parsed).
  • Leading and trailing spaces in the argument are ignored.
  • If the argument’s first character can’t be converted to a number (it’s not any of the above characters), parseFloat returns NaN.
  • parseFloat can also parse and return Infinity.
  • parseFloat converts BigInt syntax to Numbers, losing precision. This happens because the trailing n character is discarded.

Consider Number(value) for stricter parsing, which converts to NaN for arguments with invalid characters anywhere.

parseFloat will parse non-string objects if they have a toString or valueOf method. The returned value is the same as if parseFloat had been called on the result of those methods.

Examples

parseFloat returning a number

The following examples all return 3.14:

parseFloat(3.14);
parseFloat('3.14');
parseFloat('  3.14  ');
parseFloat('314e-2');
parseFloat('0.0314E+2');
parseFloat('3.14some non-digit characters');
parseFloat({ toString: function() { return "3.14" } });

parseFloat returning NaN

The following example returns NaN:

parseFloat('FF2');

parseFloat and BigInt

The following examples both return 900719925474099300, losing precision as the integer is too large to be represented as a float:

parseFloat(900719925474099267n);
parseFloat('900719925474099267n');

Specifications

Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition.
ECMAScript 5.1 (ECMA-262)
The definition of 'parseFloat' in that specification.
Standard
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'parseFloat' in that specification.
Standard
ECMAScript Latest Draft (ECMA-262)
The definition of 'parseFloat' in that specification.
Draft

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
parseFloatChrome Full support YesEdge Full support YesFirefox Full support 1IE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support 4Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yesnodejs Full support Yes

Legend

Full support  
Full support

See also

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