CSS Properties and Values API

The CSS Properties and Values API — part of the CSS Houdini umbrella of APIs — allows developers to explicitly define their CSS custom properties, allowing for property type checking, default values, and properties that do or do not inherit their value.

Interfaces

CSS.registerProperty

Defines how a browser should parse CSS custom properties. Access this interface through CSS.registerProperty in JavaScript.

@property

Defines how a browser should parse CSS custom properties. Access this interface through @property at-rule in CSS.

Examples

The following will register a custom property named --my-color using CSS.registerProperty in JavaScript. --my-color will use the CSS color syntax, it will have a default value of #c0ffee, and it will not inherit its value:

js
window.CSS.registerProperty({
  name: "--my-color",
  syntax: "<color>",
  inherits: false,
  initialValue: "#c0ffee",
});

The same registration can take place in CSS using the @property at-rule:

css
@property --my-color {
  syntax: "<color>";
  inherits: false;
  initial-value: #c0ffee;
}

Specifications

Browser compatibility

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See also