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 |
---|---|---|
DOM The 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.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
keys | Chrome Full support 45 | Edge Full support ≤79 | Firefox Full support 50 | IE No support No | Opera Full support 32 | Safari Full support 10 | 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 | Samsung Internet Android Full support 5.0 |
Legend
- Full support
- Full support
- No support
- No support