The length read-only property of the DOMTokenList interface is an integer representing the number of objects stored in the object.




An integer.


In the following example we retrieve the list of classes set on a <span> element as a DOMTokenList using Element.classList, then write the length of the list 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 length = classes.length;

span.textContent = 'classList length = ' + length;

The output looks like this:


Specification Status Comment
The definition of 'length' in that specification.
Living Standard Initial definition

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) 50 (50) ? (Yes) ?
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic NodeList (Yes) (Yes) 50.0 (50) ? (Yes) ?

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, jpmedley
 Last updated by: chrisdavidmills,