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DOMTokenList: keys() method

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

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
keys 42 16 50 No 29 10.1 42 42 50 29 10.3 4.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList/keys