Thekeys() method of theDOMTokenList interfacereturns aniterator allowing to go through all keys contained in this object.The keys are unsigned integers.

Syntax

keys()

Parameters

None.

Return value

Returns aniterator.

Examples

In the following example we retrieve the list of classes set on a<span> element as aDOMTokenList usingElement.classList. We then retrieve an iterator containing the keys usingkeys(),then iterate through those keys using afor...of loop,writing each one to the<span>'sNode.textContent.

First, the HTML:

<span></span>

Now the #"span");const classes = span.classList;const iterator = classes.keys();for (let value of iterator) { span.textContent += `(${value}) `;}