CSSMathSum
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The CSSMathSum interface of the CSS Typed Object Model API represents the result obtained by calling add(), sub(), or toSum() on CSSNumericValue.
A CSSMathSum is the object type returned when the StylePropertyMapReadOnly.get() method is used on a CSS property whose value is created with a calc() function.
Constructor
CSSMathSum()-
Creates a new
CSSMathSumobject.
Instance properties
Also inherits properties from its parent interface, CSSMathValue.
CSSMathSum.values-
Returns a
CSSNumericArrayobject which contains one or moreCSSNumericValueobjects.
Static methods
Also inherits methods from its parent interface, CSSMathValue.
Instance methods
Also inherits methods from its parent interface, CSSMathValue.
Examples
We create an element with a width determined using a calc() function, then console.log() the operator and values, and dig into the values a bit.
<div>has width</div>
We assign a width
div {
width: calc(30% - 20px);
}
We add the JavaScript
const styleMap = document.querySelector("div").computedStyleMap();
console.log(styleMap.get("width")); // CSSMathSum {values: CSSNumericArray, operator: "sum"}
console.log(styleMap.get("width").operator); // 'sum'
console.log(styleMap.get("width").values); // CSSNumericArray {0: CSSUnitValue, 1: CSSUnitValue, length: 2}
console.log(styleMap.get("width").values[0]); // CSSUnitValue {value: 30, unit: "percent"}
console.log(styleMap.get("width").values[0].value); // 30
console.log(styleMap.get("width").values[0].unit); // 'percent'
console.log(styleMap.get("width").values[1]); // CSSUnitValue {value: -20, unit: "px"}
console.log(styleMap.get("width").values[1].value); // -20
console.log(styleMap.get("width").values[1].unit); // 'px'
The specification is still evolving. In the future we may write the last three lines as:
console.log(styleMap.get("width").values[1]); // CSSMathNegate {value: CSSUnitValue, operator: "negate"}
console.log(styleMap.get("width").values[1].value); // CSSUnitValue {value: 20, unit: "px"}
console.log(styleMap.get("width").values[1].value.unit); // 'px'
Specifications
| Specification |
|---|
| CSS Typed OM Level 1 # cssmathsum |