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https://github.com/silverstripe/silverstripe-framework
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git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@92569 467b73ca-7a2a-4603-9d3b-597d59a354a9
104 lines
3.6 KiB
Markdown
104 lines
3.6 KiB
Markdown
# JavaScript Tree Control
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## Maintainers
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* Sam Minnee (sam at silverstripe dot com)
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## Features
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* Build trees using semantic HTML and unobtrusive JavaScript.
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* Style the tree to suit your application you with CSS.
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* Demo: http://www.silverstripe.org/assets/tree/demo.html
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## Usage
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The first thing to do is include the appropriate JavaScript and CSS files:
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<code html>
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<link rel="stylesheet" type="text/css" media="all" href="tree.css" />
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<script type="text/javascript" src="tree.js"></script>
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</code>
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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"`.
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Here's the HTML code that I inserted to create the demo tree above.
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<code html>
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<ul class="tree">
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<li><a href="#">item 1</a>
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<ul>
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<li><a href="#">item 1.1</a></li>
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<li class="closed"><a href="#">item 1.2</a>
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<ul>
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<li><a href="#">item 1.2.1</a></li>
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<li><a href="#">item 1.2.2</a></li>
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<li><a href="#">item 1.2.3</a></li>
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</ul>
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</li>
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<li><a href="#">item 1.3</a></li>
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</ul>
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</li>
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<li><a href="#">item 2</a>
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<ul>
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<li><a href="#">item 2.1</a></li>
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<li><a href="#">item 2.2</a></li>
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<li><a href="#">item 2.3</a></li>
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</ul>
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</li>
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</ul>
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</code>
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Your tree is now complete!
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## How it works
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Obviously, this isn't a complete detail of everything that's going on, but it gives you an insight into the overall process.
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### Starting the script
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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
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### Finding the tree content
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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".
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### Augmenting the HTML
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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.
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So, the following HTML:
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<code html>
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<li>
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<a href="#">My item</a>
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</li>
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</code>
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Is turned into the more ungainly, and yet more easily styled:
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<code html>
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<li>
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<span class="a"><span class="b"><span class="c">
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<a href="#">My item</a>
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</span></span></span>
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</li>
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</code>
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Additionally, some helper classes are applied to the `<li>` and `<span class="a">` elements:
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* `"last"` is applied to the last node of any subtree.
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* `"children"` is applied to any node that has children.
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### Styling it up
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Why the heck do we need 5 styling elements? Basically, because there are 5 background-images to apply:
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* li: A repeating vertical line is shown. Nested <li> tags give us the multiple vertical lines that we need.
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* span.a: We overlay the vertical line with 'L' and 'T' elements as needed.
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* span.b: We overlay '+' or '-' signs on nodes with children.
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* span.c: This is needed to fix up the vertical line.
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* a: Finally, we apply the page icon.
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### Opening / closing nodes
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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. |