CSSKeywordValue: CSSKeywordValue() constructor

new CSSKeywordValue(val)

#myElement {
  display: flex;
}

<div id="myElement">
  Check the developer tools to see the log in the console and to inspect the
  style attribute on this div.
</div>

const keyword = new CSSKeywordValue("initial");
const myElement = document.getElementById("myElement").attributeStyleMap;
myElement.set("display", keyword);
console.log(myElement.get("display").value); // 'initial'
console.dir(keyword);