This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The CSS.registerProperty()
method registers custom properties
, allowing for property type checking, default values, and properties that do or do not inherit their value.
Registering a custom property allows you to tell the browser how the custom property should behave; what are allowed types, whether the custom property inherits its value, and what the default value of the custom property is.
Syntax
CSS.registerProperty(PropertyDefinition);
Parameters
A PropertyDefinition
dictionary object, which can contain the following members:
name
- A
DOMString
indicating the name of the property being defined. syntax
Optional- A
DOMString
representing the expected syntax of the defined property. Defaults to "*". inherits
- A boolean value defining whether the defined property should be inherited (
true
), or not (false
). Defaults tofalse
. initialValue
Optional- A
DOMString
representing the initial value of the defined property.
Return value
undefined
.
Exceptions
InvalidModificationError
- The given
name
has already been registered. SyntaxError
- The given
name
isn't a valid custom property name (starts with two dashes, e.g.--foo
). TypeError
- The required
name
and/orinherits
dictionary members were not provided.
Examples
The following will register a custom property
, --my-color
, using registerProperty()
, as a color, give it a default value, and have it not inherit its value:
window.CSS.registerProperty({ name: '--my-color', syntax: '<color>', inherits: false, initialValue: '#c0ffee', });
In this example, the custom property --my-color
has been registered using the syntax <color>
. We can now use that property to transition a gradient on hover or focus. Notice that with the registered property the transition works, but that it doesn't with the unregistered property!
.registered { --my-color: #c0ffee; background-image: linear-gradient(to right, #fff, var(--my-color)); transition: --my-color 1s ease-in-out; } .registered:hover, .registered:focus { --my-color: #b4d455; } .unregistered { --unregistered: #c0ffee; background-image: linear-gradient(to right, #fff, var(--unregistered)); transition: --unregistered 1s ease-in-out; } .unregistered:hover, .unregistered:focus { --unregistered: #b4d455; } button { font-size: 3vw; }
We can add these styles to some buttons:
<button class="registered">Background Registered</button> <button class="unregistered">Background Not Registered</button>
Specifications
Specification | Status | Comment |
---|---|---|
CSS Properties and Values API Level 1 The definition of 'The registerProperty() function' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
registerProperty | Chrome Full support 78 | Edge Full support 79 | Firefox No support No | IE No support No | Opera Full support 65 | Safari No support No | WebView Android Full support 78 | Chrome Android Full support 78 | Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android Full support 12.0 |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
- Experimental. Expect behavior to change in the future.