DOMTokenList: keys() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The keys() method of the DOMTokenList interface returns an iterator allowing to go through all keys contained in this object. The keys are unsigned integers.

Syntax

js
keys()

Parameters

None.

Return value

Returns an iterator.

Examples

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:

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

Now the JavaScript:

js
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:

Specifications

No specification found

No specification data found for api.DOMTokenList.keys.
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Browser compatibility

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desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
keys

Legend

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Full support
Full support

See also