Ninedays Blog

Back to the basics. We're going to create a div, and hide and show it using the toggle functionality and hide and show functions with Prototype.

As with most of my teaching/tutorial style I will walk you through the progression from doing things the quick and dirty way to the more sophisticated feature fancy way. Please view the source, steal the code and go play. Any non-inline JavaScript will be included near the example that it works with, just so y'all can jack my code easier. K?

In our first example we have a feature box that is already visible and two separate actions, a hide and a show (Example 1). This entire example uses only inline JavaScript and the included prototype.js file.

Example 1 - Hide and Show with Separate Buttons

Hide Feature Box | Show Feature Box

Example 1 - Code

HTML & JavaScript

<p><a href="#" onclick="$('featurebox-1').hide();">Hide Feature Box</a> | 
<a href="#" onclick="$('featurebox-1').show();">Show Feature Box</a></p>
<div class="featurebox" id="featurebox-1"><strong>FeatureBox</strong> - Lorem ipsum dolor sit amet[...]</div>

Now let's use Prototype's built in toggle function, which toggles the visibility of an element. No fancy JavaScript function to check for visibility and then make a decision, this is all built into the library (Example 2). This entire example uses only inline JavaScript and the included prototype.js file

Example 2 - Hide and Show with a Single Toggle

Toggle Feature Box

Example 2 - Code

HTML & JavaScript

<p><a href="#" onclick="$('featurebox-2').toggle();">Toggle Feature Box</a></p>
<div class="featurebox" id="featurebox-2"><h3>
    <h3>A h3 level heading inside a "featurebox" div</h3>
    <p>A normal paragraph of text[…]</p>
</div>

Now I don't know about you but I'm tired of getting bounced to the top of the screen or reloading the page every time I click on one of those actions (hide, show or toggle) SO I am going to create a JavaScript function to listen for an even to click on a span instead of an action to happen onclick for an anchor tag. (Example 3). The listener example uses the below JavaScript function and the included prototype.js file and that span has the id 'featurebox-3-listen' applied to it.

JavaScript

<script type="text/javascript">
    Event.observe(window, 'load', function() {
        Event.observe('featurebox-3-listen', 'click', function(){
            $('featurebox-3').toggle();
        });
    });
</script>

Additional information about Event.observe is further detailed in the Event Observe and Event Listeners with Prototype Tutorial.

The inline example just has the onclick attribute of the span element set to toggle, just as the onclick attribute worked on the anchor tags in the above examples.

Example 3 - Adding a Listener, Removing the Anchor

Toggle Feature Box (Listener) | Toggle Feature Box (Inline)

Example 3 - Code

JavaScript

<script type="text/javascript">
Event.observe(window, 'load', function() {
    Event.observe('featurebox-3-listen', 'click', function(){
        $('featurebox-3').toggle();
    });
});
</script>

HTML & JavaScript

<p><span id="featurebox-3-listen">Toggle Feature Box (Listener)</span> | 
<span onclick="$('featurebox-3').toggle();">Toggle Feature Box (Inline)</span></p>
<div class="featurebox" id="featurebox-3"><div class="featurebox" id="featurebox-2">
    <h3>A h3 level heading inside a "featurebox" div</h3>
    <p>A normal paragraph of text[…]</p>
</div>

Now that we have the span listener, and toggle ability down pat, let's change the language of the span to represent the action it will take if you click it.
Here we will introduce a new function built into the library: visible()
Visible measures the visibility of an element and returns the value of true of false.

We'll use the returned value of visible() to determine what the span should now read and the update() function to change the inner html of the feature-4-listen text.

JavaScript

<script type="text/javascript">
    Event.observe('featurebox-4-listen', 'click', function(){
        $('featurebox-4').toggle();
        if($('featurebox-4').visible()){
            […]
        }
    }); 
</script>

Update VS. replace -

When trying to figure out how to replace the content (inner HMTL) in the span there were two functions I ran some tests on: update() and replace(). Update will just effect the characters contained in the element you are calling it on, where as replace will replace the whole element.

When I replaced the whole element and kept it as a span with the id of featurebox-4-listen suddenly the listener would no longer work. That is why update() is clearly the correct choice in which function to use. Plus it is far lower maintenance in the coding of the listener function above!

Now you can see that the span that toggles the visibility of the feature box will change to reflect the state of the box.

Example 4 - Toggle with Text Change

Toggle Feature Box (Listener)

Example 4 - Code

JavaScript

<script type="text/javascript">
Event.observe(window, 'load', function() {
    Event.observe('featurebox-4-listen', 'click', function(){
        $('featurebox-4').toggle();
        if($('featurebox-4').visible()){
            $('featurebox-4-listen').update('Toggle Feature Box (Close)');
        } else {
            $('featurebox-4-listen').update('Toggle Feature Box (Open)');
        }
    });
});
</script>

HTML

<p><span id="featurebox-4-listen">Toggle Feature Box (Listener)</span></p>
<div class="featurebox" id="featurebox-4"><div class="featurebox" id="featurebox-2">
    <h3>A h3 level heading inside a "featurebox" div</h3>
    <p>A normal paragraph of text[…]</p>
</div>

So you think we've learned enough yet? Not by a long shot!
There's two more items to cover before we've taken control of Prototype's ability to hide and show elements. Let's use an image to act as our toggling link, and let's start the feature box as hidden!

First to ensure the feature box in question is hidden to start let's add that to out listener. Since out listener first looks to make sure the window has loaded (in entirety) and then looks to see if the feature-box-5-listen has been clicked on we will add a command to hide featurebox-5 inside the window load listener, but before the click listener.

JavaScript

<script type="text/javascript">
    Event.observe(window, 'load', function() {
        $('featurebox-5').hide();
        Event.observe('featurebox-5-listen', 'click', function(){
            […]
        });
    });
</script>

Now to replace the span with an image. Instead of hard coding the image into the page let's leave my span coded exactly as the above examples. A span with an id of featurebox-5. The same way we defaulted the feature box to hidden we will update the span to contain an image instead of text.

Why update the span with an image instead of just starting with an image? Earlier I had mentioned that the event listener would not work when you replace the element you are listening for, even if you continue to include that id in the replacement. For this reason it is faster/easier/more reliable to put the image inside the span to ensure that when the image is changed, either initially or on toggle, the listener will still effect the functionality.

Example 5 - Toggle with Image Change

(remember we started with it closed first this time)

Example 5 - Code

JavaScript

<script type="text/javascript">
    Event.observe(window, 'load', function() {
        $('featurebox-5').hide();
        $('featurebox-5-listen').update('<img src="/uploads/2007/12/add.png" alt="Open the feature box" />');
        Event.observe('featurebox-5-listen', 'click', function(){
            $('featurebox-5').toggle();
            if($('featurebox-5').visible()){
                $('featurebox-5-listen').update('<img src="/uploads/2007/12/delete.png" alt="Close the feature box" />');
            } else {
                $('featurebox-5-listen').update('<img src="/uploads/2007/12/add.png" alt="Open the feature box" />');
            }
        });
    });
</script>

HTML

<p><span id="featurebox-5-listen">Toggle Feature Box (Listener)</span></p>
<div class="featurebox" id="featurebox-5">
    <h3>A h3 level heading inside a "featurebox" div</h3>
    <p>A normal paragraph of text[…]</p>
</div>

Example 5b - An Alternative Script for Toggle Image Changes (for Prototype 1.6+)

This is actually the one I have to use in example #5 above, to avoid problems with my blog's plugin syntax editor.
This sample has very different HTML and uses JavaScript to replace the SRC of the image as well as the ALT tag instead of replacing the whole span. The HTML names the image toggle itself as the listener instead of a surrounding div.

Example 5b - Code

JavaScript

<script type="text/javascript">
    Event.observe(window, 'load', function() {
        $('featurebox-5').hide();
        $('featurebox-5-listen').writeAttribute(src, '/uploads/2007/12/add.png');
        Event.observe('featurebox-5-listen', 'click', function(){
            $('featurebox-5').toggle();
            if($('featurebox-5').visible()){
                $('featurebox-5-listen').writeAttribute(src, '/uploads/2007/12/delete.png');
            } else {
                $('featurebox-5-listen').writeAttribute(src, '/uploads/2007/12/add.png');
            }
        });
    });
</script>

HTML

<p><img id="featurebox-5-listen"  alt="toggler"/></p>
<div class="featurebox" id="featurebox-5">
    <h3>A h3 level heading inside a "featurebox" div</h3>
    <p>A normal paragraph of text[…]</p>
</div>

I start out the toggle button with a fake image innitially (xxx.jpg) for testing to ensure the add.png image is being updated in line 3 of the JavaScript. Then I'll change it once I push the page live.

Summary

To really wrap that up, we see how Prototype can easily toggle showing and hiding a div, and changing the language in the span that does the toggling. Also we've seen how we can have the div start as hidden only if the prototype script is working properly. Don't forget that we know how to change the image if you should choose to use two different images to instead of a span to toggle the div hidden/visible.

Prototype Functions Used

• Element.hide()
• Element.show()
• Element.toggle()
• Element.update()
• Element.visible()
• Element.writeAttribute()
• Event.observe

Prototype Functions Mentioned

• Element.replace()

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