Web/API/DOMTokenList/keys

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

Syntax

tokenList.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 when retrieve an iterator containing the keys using values(), 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:

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

for(var value of iterator) {
  span.textContent += value + ' ++ ';
}

The output looks like this:

Specifications

Specification	Status	Comment
DOMThe definition of 'keys() (as iterable<Node>)' in that specification.	Living Standard	Initial definition

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
keys	Chrome Full support 42	Edge Full support 16	Firefox Full support 50	IE No support No	Opera Full support 32	Safari Full support 10.1	WebView Android Full support 45	Chrome Android Full support 45	Firefox Android Full support 50	Opera Android Full support 32	Safari iOS Full support 10.3	Samsung Internet Android Full support 5.0

Legend

Full support  

Full support

No support  

No support

DOMTokenList.keys() by Mozilla Contributors is licensed under CC-BY-SA 2.5.