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tree.js |
JavaScript Tree Control
Maintainers
- Sam Minnee (sam at silverstripe dot com)
Features
- Build trees using semantic HTML and unobtrusive JavaScript.
- Style the tree to suit your application you with CSS.
- Demo: http://www.silverstripe.org/assets/tree/demo.html
Usage
The first thing to do is include the appropriate JavaScript and CSS files:
<code html>
<link rel="stylesheet" type="text/css" media="all" href="tree.css" />
<script type="text/javascript" src="tree.js"></script>
</code>
Then, create the HTML for you tree. This is basically a nested set of bullet pointed links. The "tree" class at the top is what the script will look for. Note that you can make a tree node closed to begin with by adding class="closed"
.
Here's the HTML code that I inserted to create the demo tree above.
<code html>
<ul class="tree">
<li><a href="#">item 1</a>
<ul>
<li><a href="#">item 1.1</a></li>
<li class="closed"><a href="#">item 1.2</a>
<ul>
<li><a href="#">item 1.2.1</a></li>
<li><a href="#">item 1.2.2</a></li>
<li><a href="#">item 1.2.3</a></li>
</ul>
</li>
<li><a href="#">item 1.3</a></li>
</ul>
</li>
<li><a href="#">item 2</a>
<ul>
<li><a href="#">item 2.1</a></li>
<li><a href="#">item 2.2</a></li>
<li><a href="#">item 2.3</a></li>
</ul>
</li>
</ul>
</code>
Your tree is now complete!
How it works
Obviously, this isn't a complete detail of everything that's going on, but it gives you an insight into the overall process.
Starting the script
In simple situations, creating an auto-loading script is a simple matter of setting window.onload to a function. But what if there's more than one script? To this end, we created an appendLoader() function that will execute multiple loader functions, including a previously defined loader function
Finding the tree content
Rather than write a piece of script to define where your tree is, we've tried to make the script as automatic as possible - it finds all ULs with a class name containing "tree".
Augmenting the HTML
Unfortunately, an LI containing an A isn't sufficient for doing all of the necessary tree styling. Rather than force people to put non-semantic HTML into their file, the script generates extra <span>
tags.
So, the following HTML:
<code html>
<li>
<a href="#">My item</a>
</li>
</code>
Is turned into the more ungainly, and yet more easily styled:
<code html>
<li>
<span class="a"><span class="b"><span class="c">
<a href="#">My item</a>
</span></span></span>
</li>
</code>
Additionally, some helper classes are applied to the <li>
and <span class="a">
elements:
"last"
is applied to the last node of any subtree."children"
is applied to any node that has children.
Styling it up
Why the heck do we need 5 styling elements? Basically, because there are 5 background-images to apply:
- li: A repeating vertical line is shown. Nested
- tags give us the multiple vertical lines that we need.
- span.a: We overlay the vertical line with 'L' and 'T' elements as needed.
- span.b: We overlay '+' or '-' signs on nodes with children.
- span.c: This is needed to fix up the vertical line.
- a: Finally, we apply the page icon.
Opening / closing nodes
Having come this far, the "dynamic" aspect of the tree control is very trivial. We set a "closed" class on the <li>
and <span class="a">
elements, and our CSS takes care of hiding the children, changing the - to a + and changing the folder icon.