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 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:

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

No specification found

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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
32
10.1
45
45
50
32
10.3
5.0

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https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList/keys