DOMTokenList.keys()

None.

Returns an iterator.

In the following example we retrieve the list of classes set on a <span> element as a DOMTokenList using Element.classList. We then retrieve an iterator containing the keys using keys(), then iterate through those keys using a for...of loop, writing each one to the <span>'s Node.textContent.

First, the HTML:

<span class="a b c"></span>

Now the JavaScript:

const span = document.querySelector("span");
const classes = span.classList;
const iterator = classes.keys();

for (let value of iterator) {
  span.textContent += `(${value}) `;
}

The output looks like this:

• DOMTokenList.entries(), DOMTokenList.forEach() and DOMTokenList.values.