TreeTable的简单实现

最终效果图：


UI说明：针对table本身进行增强的tree table组件。
tree的数据来源是单元格内a元素的自定义属性：level和type。具体代码如下：

<table id="treeGrid" border="0" cellpadding="0" cellspacing="0">
  <THEAD>
  		<tr><th>Department</th><th>EmployeeID</th><th>position</th></tr>	
  </THEAD>
  <TBODY>
		<tr><td width="250px"><a level="0" type="node" href="javascript:void(0);">Dept4</a></td><td>-</td><td>-</td></tr>
		<tr><td><a level="1" type="leaf" href="javascript:void(0);">fanggw</a></td><td>c3025</td><td>MASTER</td></tr>
		<tr><td><a level="1" type="node" href="javascript:void(0);">team1</a></td><td>-</td><td>-</td></tr>
		<tr><td><a level="2" type="leaf" href="javascript:void(0);">zhanghy</a></td><td>c3268</td><td>SE</td></tr>
		<tr><td><a level="2" type="leaf" href="javascript:void(0);">chenf</a></td><td>c3401</td><td>SE</td></tr>
   </TBODY>
</table>

根据上述数据源结构，先遍历该table，读取数据并建立整课树的数据模型，然后初始化整棵树的视图（node和leaf的显示由css样式定义，方便修改，如果需要可以进一步在初始化的时候由外部代码指定），并关联节点的click处理程序。

下面是主要的实现代码：

		
		var Class = {
		  create: function() {
		    return function() {
		      this.initialize.apply(this, arguments);
		    }
		  }
		}
    
    var Node = Class.create();
    Node.prototype = {
    	initialize: function(link, level, type) {
    		this.name = link.innerText;      
			  this.id;
			  this.link = link;
			  this.type = type;
			  this.level = level;	
			  this.isOpen = true;
			  this.isClicked = false;
			  this.root;
			  this.img;	//clicked img's path

				this.parent;
			  this.children = new Array();
			  this.getChildren();
			  
    	},
    	
    	getChildren: function() {
    		if (this.type == "node") {
    			//alert(this.link.innerText);
	    		var dataRows = document.getElementById("treeGrid").getElementsByTagName("TBODY")[0].getElementsByTagName("TR");
	    		var pushFlag = false;
	    		
	    		for(var j=0; j<dataRows.length; j++) {
	    			var linkTag = dataRows[j].firstChild.firstChild;
	    			var level = linkTag.getAttribute("level");
	    			var type = linkTag.getAttribute("type");
	    			
	    			if (!pushFlag) {
	    				if (linkTag == this.link) {
	    					pushFlag = true;
	    				}
	    				continue;
	    			}
	    			//alert("cur lvl:"+level+"; type:"+type +" ;parentLvl:" +(parseInt(this.level)+1));
	    			
	    			if (level == (parseInt(this.level)+1)) {
	    				//alert("push node's lvl:"+level+"; type:"+type);
	    				var leaf = new Node(linkTag, level, type);
	    				leaf.parent = this;
	    				leaf.id = level+"_"+j;
	    				this.children.push(leaf);
	    			} else if (level == this.level) {
	    				break;
	    			} else {
	    				continue;
	    			}
	    			
	    		}
    		}
    		//for (var i=0; i<this.children.length; i++) {
    			//this.children[i].parent = this;
    		//}
    		//alert("childs:"+this.children.length);
    	},
    	
    	getNext: function() {
    		var next = null;
    		//alert(this.name);
    		
    		if (this.parent) {
	    		for (var i=0; i<this.parent.children.length; i++) {
	    			if (this.parent.children[i] == this && i < (this.parent.children.length-1)) {
	    				next = this.parent.children[i+1];
	    				break;
	    			}
	    		}	
    		}
    		/*
    		if (next)
    			alert("next:"+next.name);
    		else 
    			alert("current is last");
    		*/
    		return next;
    	},
    	
    	
    	getCurrentRow: function() {
				return this.link.parentNode.parentNode.parentNode;   		
    	},
    	
    	changeClickImg: function() {
    		if (this.isOpen) {
    			this.img.src = this.img.src.replace("minus", "plus");
    		} else {
    			this.img.src = this.img.src.replace("plus","minus");
    		}
    		this.isOpen = this.isOpen?false:true;
    	},
    	
    	getInnerHTML: function() {
    		var oFragment = document.createDocumentFragment();
    		
    		//make the indent img by level
	    	for (var lvl = this.level-1; lvl>0; lvl--) {
	    		var indentImg = document.createElement("img");
	    		
	    		//get parent node by level
	    		var parentNode = this.parent;
	    		for (var i=1; i<lvl; i++) {
	    			parentNode = parentNode.parent;
	    		}
	    		
	    		//alert(this.name+":"+parentNode.name);
	    		//alert(parentNode.getNext()?parentNode.getNext().name:"null");
	    		
	    		/* parent node has nextSibling insert vertical line img */
	    		if (parentNode.getNext()) {
	    			indentImg.src = "./images/I.gif";
	    		} else {
	    			/* parent node has nextSibling insert blank img */
	    			indentImg.src = "./images/blank.gif";
	    		}
    			indentImg.align = "absbottom";
					oFragment.appendChild(indentImg);
    		}

    		
    		//make the plus or minus img
    		var img = document.createElement('img');
    		var path;
    		if (this.type == "node") {
    			if (this.level == 0) {
    				path = "./images/minus.gif";
    			} else {
    				if (this.children.length > 0) {
    					if (this.getNext()) {
    						path = "./images/Tminus.gif";
    					} else {
    						path = "./images/Lminus.gif";
    					}
    				}
    				else {
    					if (this.getNext()) {
    						path = "./images/T.gif";
    					} else {
    						path = "./images/L.gif";
    					}
    				}
    			}    			
    		} else {
  				if (this.getNext()) {
  					path = "./images/T.gif";
  				}
  				else {
  					path = "./images/L.gif";
  				} 
    		}
    		img.src = path;
			  img.align = "absbottom";
			  //set cursor pointer style to the minus/plus img
			  img.style.cursor = "pointer"
			  this.img = img;
			  img.onclick = expand;
			  
			  oFragment.appendChild(img);
			  oFragment.appendChild(this.link);
			  
			  var div = document.createElement("div");
			  div.setAttribute("id", this.id);

			  /* div css class set by type */
			  div.className = (this.type=="node")?"node":"leaf"; 
			  
			  /* all node is margin to left by 10 pixel except root */
			  if (this.level > 0) {
				  div.style.marginLeft = "10px";
			  }
			  
				div.appendChild(oFragment);
				return div;
    		
    	}
    }
    
    /* global variable */
    //tree root
    var root;
    //all nodes of the tree
    var nodes = new Array();
    
    /* initialize the whole tree grid */
    function initTreeGrid() {
		  //dataRows is the datasource of the tree
			var dataRows = document.getElementById("treeGrid").getElementsByTagName("TBODY")[0].getElementsByTagName("TR");
    	
    	//find the root of the tree
    		for (var i=0; i<dataRows.length; i++) {
    			var linkTag = dataRows[i].firstChild.firstChild;
    			var level = linkTag.getAttribute("level");
    			var type = linkTag.getAttribute("type");
    			
    			if (level == 0 && type == "node") {
	  				var root = new Node(linkTag, 0, "node");
	  				root.parent = null;
	  				root.id = "0_0";
						break;
    			}
    		}
    		
    		//put all node into 1-index array
    		nodes.push(root);
    		initNodes(root);
    		
    		//display the table tree
    		for (var j = 0; j<nodes.length; j++) {
    			dataRows[j].firstChild.appendChild(nodes[j].getInnerHTML());
    		}
    }
    
    function initNodes(node) {
    	  for (var j=0; j<node.children.length; j++) {
    			nodes.push(node.children[j]);
    			if (node.children[j].children.length > 0) {
    				initNodes(node.children[j]);
    			}
    		}
    }
    
    /* expand row elements by isOpen flag */
    function expand() {    	
    	var currentDivId = event.srcElement.parentNode.id;
    	var currentNode;
    	
    	//get the clicked node
    	for(var i=0; i<nodes.length; i++) {
    		if (currentDivId == nodes[i].id) {
    			currentNode = nodes[i];
    			break;
    		}
    	}
    	
    	//expand the clicked node
    	expandChild(currentNode);
    	
    	//set the isClicked flag when the row minus img is clicked
    	currentNode.isClicked = currentNode.isClicked?false:true;
    }
    
    function expandChild(currentNode) {
    	//alert(currentNode.name);
    	for (var i=0; i<currentNode.children.length; i++) {
    		var child = currentNode.children[i];
    		if (child.type == "node" && !child.isClicked) {
    			expandChild(child);
    		}
    		child.getCurrentRow().style.display = currentNode.isOpen?"none":"block";
    	}
    	currentNode.changeClickImg();
    }
		
		/* utility function */
		function addEvent(obj, evType, fn) {
		    /* adds an eventListener for browsers which support it
		       Written by Scott Andrew: nice one, Scott */
		    if (obj.addEventListener) {
		        obj.addEventListener(evType, fn, true);
		        return true;
		    }
		    else if (obj.attachEvent) {
			    var r = obj.attachEvent("on"+evType, fn);
		        return r;
		    }
		    else {
			    return false;
		    }
		}
		
		/* add load event to body element*/
		addEvent(window, "load", initTreeGrid);

该组件已在IE6+，Firefox上测试通过。
有兴趣的朋友可以联系我，进行进一步的改进和扩展。