syntax
Baseline 2024
Newly available
Since July 2024, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
The syntax
CSS descriptor is required when using the @property
at-rule and describes the allowable syntax for the property.
Syntax
The following are all valid syntax strings:
syntax: "<color>"; /* accepts a color */
syntax: "<length> | <percentage>"; /* accepts lengths or percentages but not calc expressions with a combination of the two */
syntax: "small | medium | large"; /* accepts one of these values set as custom idents. */
syntax: "*"; /* any valid token */
Values
A string with a supported syntax as defined by the specification. Supported syntaxes are a subset of CSS types. These may be used alone, or a number of types can be used in combination.
"<length>"
-
Any valid
<length>
values. "<number>"
-
Any valid
<number>
values. "<percentage>"
-
Any valid
<percentage>
values. "<length-percentage>"
-
Any valid
<length-percentage>
values. "<color>"
-
Any valid
<color>
values. "<image>"
-
Any valid
<image>
values. "<url>"
-
Any valid
<url>
values. "<integer>"
-
Any valid
<integer>
values. "<angle>"
-
Any valid
<angle>
values. "<time>"
-
Any valid
<time>
values. "<resolution>"
-
Any valid
<resolution>
values. "<transform-function>"
-
Any valid
<transform-function>
values. "<custom-ident>"
-
Any valid
<custom-ident>
values. "<transform-list>"
-
A list of valid
<transform-function>
values.
Formal definition
Related at-rule | @property |
---|---|
Initial value | n/a (required) |
Computed value | as specified |
Formal syntax
syntax =
<string>
Examples
Add type checking to --my-color
custom property, using the <color>
syntax:
@property --my-color {
syntax: "<color>";
inherits: false;
initial-value: #c0ffee;
}
Using JavaScript CSS.registerProperty()
:
window.CSS.registerProperty({
name: "--my-color",
syntax: "<color>",
inherits: false,
initialValue: "#c0ffee",
});
Specifications
Specification |
---|
CSS Properties and Values API Level 1 # the-syntax-descriptor |
Browser compatibility
BCD tables only load in the browser