Note: This feature is available in Web Workers.
The value property of the CSSUnitValue interface represents the number of units.
A number.
The following code creates a CSSPositionValue from individual CSSUnitValue constructors, then queries the CSSUnitValue.value.
const pos = new CSSPositionValue(
new CSSUnitValue(5, "px"),
new CSSUnitValue(10, "px"),
);
console.log(pos.x.value); // 5
console.log(pos.y.value); // 10