The specularConstant read-only property of the SVGFESpecularLightingElement interface reflects the specularConstant attribute of the given <feSpecularLighting> element.
An SVGAnimatedNumber object.
specularConstant Property<svg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg">
<defs>
<filter id="specularLightingFilter">
<!-- Applies specular lighting with a constant specular reflectance -->
<feSpecularLighting
in="SourceGraphic"
specularConstant="0.5"
lighting-color="hotpink">
<fePointLight x="50" y="50" z="30" />
</feSpecularLighting>
</filter>
</defs>
<rect
x="20"
y="20"
width="100"
height="100"
fill="lightblue"
filter="url(#specularLightingFilter)" />
</svg>// Select the feSpecularLighting element
const specularLightingElement = document.querySelector("feSpecularLighting");
// Access the specularConstant property
console.log(specularLightingElement.specularConstant.baseVal); // Output: 0.5