CSSPrimitiveValue: setFloatValue() method

Deprecated

Avoid using this feature in new projects. The DOM level 2 CSS object model was excluded from the later CSS object model (CSSOM) specification. This feature may be a candidate for removal from web standards or browsers.

Consider using the following features instead: CSS object model.

Learn more
See full compatibility

Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

The setFloatValue() method of the CSSPrimitiveValue interface is used to set a float value. If the property attached to this value can't accept the specified unit or the float value, the value will be unchanged and a DOMException will be 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

setFloatValue(unitType, floatValue)

Parameters

unitType

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.

floatValue

A float representing the new float value.

Return value

None (undefined).

Exceptions

Type	Description
`DOMException`	An `INVALID_ACCESS_ERR` is raised if the CSS value doesn't contain a float value or if the string value can't be converted into the specified unit. A NO_MODIFICATION_ALLOWED_ERR is raised if this property is read-only.

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

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This page was last modified on May 9, 2026 by MDN contributors.

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