Toggle Element Visibility via JavaScript

By Jeff Starr on Tuesday, April 29, 2008 — 4 Responses metadata

Post #538 categorized as Function, last updated on Apr 30, 2008
Tagged with javascript, tips, tricks

Recently, while restoring the popular Jupiter! WordPress theme, which several readers use to “skin” the Perishable Press website, I found myself searching for a simple, effective JavaScript technique for toggling element visibility. Specifically, I needed to accomplish the following design goals:

• Users should be able to toggle the visibility of any division containing post-meta information
• The post-meta information should remain visible by default and when JavaScript is unavailable
• The JavaScript should be as unobtrusive as possible, requiring minimal scripting in the markup

Here are a couple of screenshots demonstrating this repetitious toggling functionality as employed in the Jupiter! theme (click on either thumbnail for larger screenshot):

Click for screenshot showing multiple visible metadata elements

Click for screenshot showing multiple hidden metadata elements

To accomplish this multiplicity of toggling elements, I employed the following threefold strategy:

1) The Toggle JavaScript

First, I placed a copy of the following toggle-element function into my site’s external JavaScript file:

// Toggle Element Visibility via JavaScript
// http://perishablepress.com/press/2008/04/29/toggle-element-visibility-via-javascript/

function toggle(x) {
	if (document.getElementById(x).style.display == 'none') {
		document.getElementById(x).style.display = '';
	} else {
		document.getElementById(x).style.display = 'none';
	}
}

Once in place, this JavaScript Toggle function takes the target element’s id as a variable and executes the following behavior:

• The toggle function first checks the CSS display style associated with the target toggling element.
• Then, if the element’s display property is declared as none, the toggle function discards the property and displays the element.
• Otherwise, if the element’s display property is declared as anything other than none (e.g., block, visible, etc.), the toggle function switches the property to none and hides the element.

2) The (X)HTML Markup

There are millions of ways to create the markup required for your average “show-hide” scenario. For my particular design needs, I created two divisions ( <div>s ), one containing the toggle link (with class="toggle_link") and another serving as the toggling element (with class="post_meta"):

<!-- division containing the toggle link -->
<div class="toggle_link">
	<a href="javascript:;" onclick="toggle('meta-<?php the_ID(); ?>');" title="Toggle (show/hide) the visibility of meta information for this post">Toggle visibility</a>
</div>

<!-- division serving as the toggling element -->
<div class="post_meta" id="meta-<?php the_ID(); ?>">
	<h4>Posted on <?php the_time('l, F d, Y'); ?></h4>
	<h4>Posted by <?php the_author(); ?></h4>
	<h4>Posted as <?php the_category(','); ?></h4>
</div>

Within the first <div>, the toggle link contains three important attributes:

• href="javascript:;" — instructs the browser to ignore the link and execute the JavaScript.
• onclick="toggle('meta-<?php the_ID(); ?>');" — triggers the JavaScript and passes the dynamically generated element id to the toggle function.
• title="Toggle (show/hide) the visibility..." — explains the purpose of the link and indicates what to expect if clicked.

Note that the id declared as the variable in the toggle function need not be dynamic as specified here. Any statically declared id will work just fine. For example, we could use something like, onclick="toggle('static_id');", or whatever.

Then, within the second <div>, the actual post-meta information is generated and displayed according to various WordPress template tags. The key to this division is the inclusion of the same dynamically generated id as is declared in the onclick="toggle('meta-<?php the_ID(); ?>');" attribute. So long as the id of the toggling element matches that declared in the function call, everything should work exactly as intended.

3) The CSS Presentation

Finally, here is the CSS applied to the toggling division (via class="post_meta"):

div.post_meta {
	display: block;
	width: 133px;
	float: left;
	clear: none;
	padding: 0;
	margin: 0;
	}

Of course, you will want to style your markup differently, however I include these styles as example and for the completion of this tutorial. For my particular design, the inclusion of the display: block; property ensures that the meta information is displayed by default and also when JavaScript is unavailable.

Wrap up..

As many of you know, there are a million ways to show and hide divisions and other elements via JavaScript. By no means I am suggesting that this technique is like the most absolute bestest method ever. The same may be said for the markup and CSS. This tutorial is intended to further understanding of toggling in general by way of a specifically applied example. This specific application works great for me, and hopefully will be adapted and extrapolated to suit the needs of others. Having said that, I realize that various aspects of the method are less than perfect, so feel free to share your insights and wisdom with the community. Cheers! :)

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