YUI Library Examples: TreeView Control: Folder-Style TreeView Design

Implementing the Folder Style for TreeVeiw

The key change we've made in this example of the TreeView Control is that we've applied a supplementary CSS file:

This CSS redefines the look of branch nodes so they appear as folders. The folder-style CSS accompanies your YUI download and can be found in the yui/examples/treeview/assets directory.

Beyond the link element referenced above, the following markup is on the page for this example:

Based on that markup, we use the following JavaScript code to create our TreeView instance, populate its nodes, and add expand/collapse functionality:

//an anonymous function wraps our code to keep our variables
//in function scope rather than in the global namespace:
(function() {
	var tree; //will hold our TreeView instance
	
	function treeInit() {
		
		YAHOO.log("Example's treeInit function firing.", "info", "example");
		
		//Hand off ot a method that randomly generates tree nodes:
		buildRandomTextNodeTree();
		
		//handler for expanding all nodes
		YAHOO.util.Event.on("expand", "click", function(e) {
			YAHOO.log("Expanding all TreeView  nodes.", "info", "example");
			tree.expandAll();
			YAHOO.util.Event.preventDefault(e);
		});
		
		//handler for collapsing all nodes
		YAHOO.util.Event.on("collapse", "click", function(e) {
			YAHOO.log("Collapsing all TreeView  nodes.", "info", "example");
			tree.collapseAll();
			YAHOO.util.Event.preventDefault(e);
		});
	}
	
	//This method will build a TreeView instance and populate it with
	//between 3 and 7 top-level nodes
	function buildRandomTextNodeTree() {
	
		//instantiate the tree:
		tree = new YAHOO.widget.TreeView("treeDiv1");
		
		//create top-level nodes
		for (var i = 0; i < Math.floor((Math.random()*4) + 3); i++) {
			var tmpNode = new YAHOO.widget.TextNode("label-" + i, tree.getRoot(), false);
			
			//we'll delegate to another function to build child nodes:
			buildRandomTextBranch(tmpNode);
		}
		
		//once it's all built out, we need to render
		//our TreeView instance:
		tree.draw();
	}

//This function adds a random number <4 of child nodes to a given
	//node, stopping at a specific node depth:
	function buildRandomTextBranch(node) {
		if (node.depth < 6) {
			YAHOO.log("buildRandomTextBranch: " + node.index);
			for ( var i = 0; i < Math.floor(Math.random() * 4) ; i++ ) {
				var tmpNode = new YAHOO.widget.TextNode(node.label + "-" + i, node, false);
				buildRandomTextBranch(tmpNode);
			}
		}
	}
	
	//When the DOM is done loading, we can initialize our TreeView
	//instance:
	YAHOO.util.Event.onDOMReady(treeInit);
	
})();//anonymous function wrapper closed; () notation executes function

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TreeView Control Examples:

More TreeView Control Resources:

All YUI 2.x users should review the YUI 2.8.2 security bulletin, which discusses a vulnerability present in YUI 2.4.0-2.8.1.