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YUI Library Examples: TreeView Control: Three Ways to Define a TreeView: Markup (Progressive Enhancement), Existing TreeView Instance, and Object Literal

TreeView Control: Three Ways to Define a TreeView: Markup (Progressive Enhancement), Existing TreeView Instance, and Object Literal

In this simple example you can see how to build TreeView Control instance from several different sources of data:

  1. an HTML list on the page;
  2. an existing TreeView instance's definition;
  3. a branch of an existing TreeView instance (e.g., from one of its nodes).

Tree from markup

  • List 0
    • List 0-0
      • item 0-0-0
      • item 0-0-1
  • item 0-1
    • YUI
      • item 0-1-0
      • item 0-1-1

Copy of the tree above taken from its own definition

Copy of the second branch of the tree at the top

Tree built from a static definition

Building trees from HTML markup or from previous definitions.

In this brief example for the TreeView Control, we begin with a <div> containing a set of nested unordered lists <ul> providing the basic tree structure

We create a new TreeView and render it. The TreeView will read the existing HTML and build the nodes from it.

Once we have a tree, we can read its definition, preserve it somehow and then build an identical tree from it. In the second part we are building a couple of trees, one identical to the full tree and another one from just a branch of it

For tree2 we have used the full tree definition from the first tree. For tree3 we have first located a branch, for this sample, the second branch from the root and used its definition for the tree

Finally, in the last tree, we used an object literal to define the full tree.

Here we provide as a second argument to the constructor an array where each item can be either an object literal or a simple string, such as 'Label 0', which will be converted to a simple TextNode.

The items in the array can also be objects containing more detailed definitions for each node. All require a type property using either a short-name such as 'Text' or 'HTML' (case-insensitive) or the object name of the node type like 'MenuNode', which will be resolved to YAHOO.widget.MenuNode.

Object definitions allow precise control over the tree since any public property of each node can be specified, for example, some nodes start expanded while others collapsed. We cannot have such expressiveness from plain HTML markup.

We have defined a couple of external links. In the first one, labeled YAHOO, the link has the generic style of the rest of the nodes in the tree. In the second one, labeled YUI, we have used an HTMLNode instead of a TextNode so TreeView copies that string into the node without adding further classNames so it gets a different look.

The last node, being a MenuNode, forces other branches to collapse when expanded. The other node with children, being a plain node doesn't mind if other nodes remain expanded.

Nodes may contain a children property containing further node definitions.

Configuration for This Example

You can load the necessary JavaScript and CSS for this example from Yahoo's servers. Click here to load the YUI Dependency Configurator with all of this example's dependencies preconfigured.

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