CSSPrimitiveValue: getFloatValue() method

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

The getFloatValue() method of the CSSPrimitiveValue interface is used to get a float value in a specified unit. If this CSS value doesn't contain a float value or can't be converted into the specified unit, a DOMException is raised.

Note: This method was part of an attempt to create a typed CSS Object Model. This attempt has been abandoned, and most browsers do not implement it.

To achieve your purpose, you can use:

the untyped CSS Object Model, widely supported, or
the modern CSS Typed Object Model API, less supported and considered experimental.

Syntax

getFloatValue(unit)

Parameters

unit

An unsigned short representing the code for the unit type, in which the value should be returned. Valid values are:

Constant	Description
`CSS_CM`	The value is a `<length>` in centimeters.
`CSS_DEG`	The value is an `<angle>` in degrees.
`CSS_DIMENSION`	The value is a `<number>` with an unknown dimension.
`CSS_EMS`	The value is a `<length>` in em units.
`CSS_EXS`	The value is a `<length>` in ex units.
`CSS_GRAD`	The value is an `<angle>` in grads.
`CSS_HZ`	The value is a `<frequency>` in Hertz. The value can be obtained by using the getFloatValue method.
`CSS_IN`	The value is a `<length>` in inches.
`CSS_KHZ`	The value is a `<frequency>` in Kilohertz.
`CSS_MM`	The value is a `<length>` in millimeters.
`CSS_MS`	The value is a `<time>` in milliseconds.
`CSS_NUMBER`	The value is a simple `<number>`.
`CSS_PC`	The value is a `<length>` in picas.
`CSS_PERCENTAGE`	The value is a `<percentage>`.
`CSS_PT`	The value is a `<length>` in points.
`CSS_PX`	The value is a `<length>` in pixels.
`CSS_RAD`	The value is an `<angle>` in radians.
`CSS_S`	The value is a `<time>` in seconds.

Return value

A float value in the specified unit.

Exceptions

Type	Description
`DOMException`	An `INVALID_ACCESS_ERR` is raised if the CSS value doesn't contain a float value or if the float value can't be converted into the specified unit.

Examples

const cs = window.getComputedStyle(document.body);
const cssValue = cs.getPropertyCSSValue("margin-top");
console.log(cssValue.getFloatValue(CSSPrimitiveValue.CSS_CM));

Specifications

This feature was originally defined in the DOM Style Level 2 specification, but has been dropped from any standardization effort since then.

It has been superseded by a modern, but incompatible, CSS Typed Object Model API that is now on the standard track.

Browser compatibility

Help improve MDN

Learn how to contribute

This page was last modified on ⁨Jun 23, 2025⁩ by MDN contributors.

View this page on GitHub • Report a problem with this content