YUI Library Home

Site Search (YDN & YUIBlog):

# YUI Library Examples: Dom Collection: Using hasClass

# Dom Collection: Using hasClass

Clicking the button will use Dom's `hasClass` method to test if the element has the class `baz` applied.

View example in new window.

foo

## Using hasClass

`hasClass`, part of the YUI Dom Collection, makes it easy to test whether a given className is present on an element.

To illustrate the use of `hasClass`, we'll create a `<div>` called `foo` with the className of `bar` and `baz`. When the button is clicked, we will test whether the `className` `baz` is present.

Add some markup for the demo element:

<div id="foo" class="bar baz">foo</div> <button id="demo-run">run</button>

Now we will define the function that tests whether `foo` has the `className` `baz` applied. The first argument of the `hasClass` method is either the ID of an HTMLElement, or an actual HTMLElement object. The second is the `className` we are testing for. The `hasClass` method returns `true` or `false`, depending on whether the `className` exists on the element. <script type="text/javascript"> var testClass = function() { alert(YAHOO.util.Dom.hasClass('foo', 'baz')); }; </script>

To trigger the demo, we will use the YUI Event Utility's `on` method to listen for clicks on the button.

<script type="text/javascript"> YAHOO.util.Event.on('demo-run', 'click', testClass); </script>

This is a simple example of how to use the `YAHOO.util.Dom.hasClass` method. One of the benefits of this method is that it works regardless of how many `className`s are present in the class attribute.

## Configuration for This Example

You can load the necessary JavaScript and CSS for this example from Yahoo's servers. Click here to load the YUI Dependency Configurator with all of this example's dependencies preconfigured.

### YUI Logger Output:

Note: You are viewing this example in debug mode with logging enabled. This can significantly slow performance.

Reload with logging
and debugging disabled.

### Dom Collection Examples:

- Using setXY
- Using getXY
- Using setStyle
- Using getStyle
- Using hasClass
- Using addClass
- Using removeClass
- Using getElementsByClassName
- Exploring the Dom Collection's API

### More Dom Collection Resources:

- User's Guide (external)
- API Documentation
- Cheat Sheet PDF (external)

Copyright © 2009 Yahoo! Inc. All rights reserved.

Privacy Policy - Terms of Service - Copyright Policy - Job Openings