Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The size read-only property of the CSSFontFeatureValuesMap interface returns a positive integer containing the size of the CSSFontFeatureValuesMap object.
A positive integer.
The following example outputs an integer of the number of the declarations within the @swash feature block. This example is using @swash but also works with other feature value blocks.
@font-feature-values "MonteCarlo" {
@swash {
swishy: 1;
swashy: 2;
}
}// get the rules
const myRule = document.styleSheets[0].cssRules[0];
console.log(myRule.swash.size); // logs 2