Show/Hide Content with CSS and JavaScript

There are plenty of reasons why you might feel the urge to wax verbose on your website’s front page: to prevent your users from having to click through to a new page to find your information, to avoid having to reload the page, or even to improve your front page’s SEO. But just because your front page is text-heavy doesn’t mean it all needs to be visible at once.

Today’s tutorial will show you how to hide away extra bits of content using CSS and JavaScript, to be revealed at the click of a button. This is a great technique, because displaying the additional content doesn’t require a refresh or navigation to a new page and all your content is still visible to search engine bots that don’t pay any attention to CSS or JavaScript.

We’ll start with structuring our XHTML appropriately:

<p>...This is all visible content... 
<a href="#" id="example-show" class="showLink" 
onclick="showHide('example');return false;">See more.</a>
</p>
<div id="example" class="more">
	<p>...This content is hidden by default...</p>
	<p><a href="#" id="example-hide" class="hideLink" 
	onclick="showHide('example');return false;">Hide this content.</a></p>
</div>

There are three things of importance here: the “show” anchor, the “hide” anchor, and our “hidden” div. Each has been given an ID and a class. The IDs are used by our JavaScript to locate and style the items appropriately. I’m then using the classes to set our “default” CSS. Technically you could just use the IDs the set that CSS as well, but if you wanted more than one hidden section on your page, that could get messy.

You’ll notice in the code above that all of our IDs are fairly similar. This is a trick I’m using to simplify our JavaScript, as you’ll see later on down the road, so I suggest doing something similar. The class names have no relationship to the JavaScript whatsoever, and could really be whatever you wanted them to be.

It’s also important to note that we’re calling our JavaScript using the “onclick” call, and passing it the name of our hidden div. Our JavaScript will use that single variable to do the rest of the work.

Now that we have our XHTML in place, let’s put together our default CSS:

.more {
	display: none;
	border-top: 1px solid #666;
	border-bottom: 1px solid #666; }
a.showLink, a.hideLink {
	text-decoration: none;
	color: #36f;
	padding-left: 8px;
	background: transparent url('down.gif') no-repeat left; }
a.hideLink {
	background: transparent url('up.gif') no-repeat left; }
a.showLink:hover, a.hideLink:hover {
	border-bottom: 1px dotted #36f; }

I’m technically doing far more styling than is necessary here, mostly for aesthetic purposes. The only truly important style is the “display: none;” rule on our .more class. This hides our extra content by default. The rest of the CSS simply adds a border to our div (the border is hidden by the display rule, but becomes visible later) and fancied up our show/hide anchors by putting down/up arrows next to them and replacing the standard underline with a dotted border. You could style these yourself however you like, and everything would still work just fine.

Next comes the JavaScript, which looks far more complicated than it is:

function showHide(shID) {
	if (document.getElementById(shID)) {
		if (document.getElementById(shID+'-show').style.display != 'none') {
			document.getElementById(shID+'-show').style.display = 'none';
			document.getElementById(shID).style.display = 'block';
		}
		else {
			document.getElementById(shID+'-show').style.display = 'inline';
			document.getElementById(shID).style.display = 'none';
		}
	}
}

Our JavaScript is doing four things here:

1. It checks to see if it can find an element with an ID that matches the variable we passed it.
2. If so, it checks to see if our “show” link is visible (this is where the ID naming convention starts to matter).
3. If the “show” link is visible, that means our content is still hidden. The JavaScript then hides the link and displays our hidden content.
4. If the “show” link is hidden, that means our extra content is currently visible. So it just reverses course, displaying our link again and hiding our extra content.

And that’s it! You can see a working example in action here.

Our job has been made much simpler by a few tricksy tricks. First off, we’re using the same function to show and hide our content, which saves us a bit of coding time. Our function simply checks on the state of things: if things are hidden, it shows them, and vice-versa.

Second, by using a defined schema for our element IDs (“example,” “example-show,” and “example-hide,” in our example above), we only need to pass our JavaScript a single variable. It then uses that variable to find all of our other elements and style them appropriately.

And finally, we put our “hide this content” anchor inside the hidden div. This means that we never have to set its display property: it’s hidden when the container is hidden, and visible when the container is. That saves us two lines of JavaScript and at least one line of CSS.

This technique could be used in loads of situations. Say for example that you have a WordPress blog and the front page shows excerpts instead of the full article. You could use this technique to have the whole article on the front page for the search engines to find, visible to your users at the click of a button. Or maybe you have a complex form that could use some detailed in-page explanation, but you don’t always want the help content visible, eating up real estate when some users already know what to do. Or… well, anything, really. Let me know if you come up with any creative uses!