SVGFESpecularLightingElement：surfaceScale 屬性

<svg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg">
  <defs>
    <filter id="specularLightingFilter">
      <!-- Adds specular lighting with a surface scale -->
      <feSpecularLighting
        in="SourceGraphic"
        specularExponent="20"
        lighting-color="hotpink"
        surfaceScale="3">
        <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 surfaceScale property
console.log(specularLightingElement.surfaceScale.baseVal); // Output: 3