打造jQuery的高性能TreeView

UPDATE:回答网友提出的设置节点的自定义图片的问题，同时欢迎大家提问，我尽量在第一时间回复，详见最后 2009-11-03

项目中经常会遇到树形数据的展现，包括导航，选择等功能，所以树控件在大多项目中都是必须的。那一个实用的树应该具备什么功能呢？

根据我的项目实践情况，主要是几个关键点：

1：支持静态的树，即一次性将全部数据加载到客户端。

2：异步树，即一次只加载一级或若干级节点，子节点可以异步加载数据。

3：Checkbox树（可能是静态树也可能是异步树），用于选择（如选择组织机构，选择数据字典项）等，最好是能够支持节点级联（这个是难点）

4：能够承载大数据量，并性能表现优异

5：能够在主流浏览器中运行良好

那我要打造的TreeView就是为了实现这个5个主要指标的。

先来看下效果图

上图是中国行政区域的数据树，总共得节点是3500+。

那么我们要开工了；

1：第一个确定的节点Dom结构（即用什么样的HTML来构建节点）

• 比较土的是table套table的（样式上好控制,但是大数据量，和层次较深的树，这种结构肯定顶不住的）
• 还有一种是比较新鲜的UL套LI的方式，这是现下很多书采取的方式如Jquery.treeview就是采用的这种格式，好处比较明显就是结构简洁明了，
  而且在不支持Js的浏览器上，同样也能呈现出树的形状（这种情况其实咱可以忽略），但是Jquery.treeview的节点在IE下，特别是IE6下无法被内部元素撑开，（IE7，8当达到一定深度时无法撑开），请奇怪的现象（我猜测是因为使用padding来做缩进，margin-left：负值来控制图标位置有关，但是修改起来难度也较大），在这种情况下书会变形（Jquery.treeview）就有这种问题，只能通过设置节点的width来解决。

JQuery.treeview的节点结构

Jquery.TreeView  IE6 下 展开第三级即出现错位

IE8下展开到第5级

• 还有一些是div套table的方式，CSDN的导航树就是这种，是种折中的方法（节点也不算太复杂，而且CSS也比较好写），如下图所示
  

而我采用的也是第二种方式，但是缩进采用了填空的方式，即缩进的位置用空白的图片填充来避免Jquery.treeview的问题

我的树节点结构

确定了节点的HTML我们就可以来写CSS了。有了效果图，有个节点结构接着就编写CSS了

下面是CSS的完整代码

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.ie .bbit-tree .bbit-tree-bwrap{   } .bbit-tree ul,.bbit-tree li {     list-style-type:none;     margin:0px;     padding:0px; } .bbit-tree-body {      font-size:12px; } .bbit-tree-icon, .bbit-tree-ec-icon, .bbit-tree-node-cb,.bbit-tree-elbow-line, .bbit-tree-elbow, .bbit-tree-elbow-end, .bbit-tree-elbow-plus, .bbit-tree-elbow-minus, .bbit-tree-elbow-end-plus, .bbit-tree-elbow-end-minus{     border: 0 none;     height: 18px;     margin: 0;     padding: 0;     vertical-align: top;     width: 16px;     background-repeat: no-repeat; }  .bbit-tree-node-cb  {      height:16px;  } .bbit-tree-node-collapsed .bbit-tree-node-icon, .bbit-tree-node-expanded .bbit-tree-node-icon, .bbit-tree-node-leaf .bbit-tree-node-icon{     border: 0 none;     height: 18px;     margin: 0;     padding: 0;     vertical-align: top;     width: 16px;     background-position:center;     background-repeat: no-repeat; }   .ie .bbit-tree-node-indent img, .ie .bbit-tree-node-icon, .ie .bbit-tree-ec-icon {     vertical-align:middle !important; }   .bbit-tree-noicon .bbit-tree-node-icon{     width:0; height:0; }   /* No line styles 没有线的样式 */ .bbit-tree-no-lines .bbit-tree-elbow{     background:transparent; }   .bbit-tree-no-lines .bbit-tree-elbow-end{     background:transparent; }   .bbit-tree-no-lines .bbit-tree-elbow-line{     background:transparent; }   /* Arrows Vista系统树的样式只有箭头*/ .bbit-tree-arrows .bbit-tree-elbow{     background:transparent; }   .bbit-tree-arrows .bbit-tree-elbow-plus{     background:transparent no-repeat 0 0; }   .bbit-tree-arrows .bbit-tree-elbow-minus{     background:transparent no-repeat -16px 0; }   .bbit-tree-arrows .bbit-tree-elbow-end{     background:transparent; }   .bbit-tree-arrows .bbit-tree-elbow-end-plus{     background:transparent no-repeat 0 0; }   .bbit-tree-arrows .bbit-tree-elbow-end-minus{     background:transparent no-repeat -16px 0; }   .bbit-tree-arrows .bbit-tree-elbow-line{     background:transparent; }   .bbit-tree-arrows .bbit-tree-ec-over .bbit-tree-elbow-plus{     background-position:-32px 0; }   .bbit-tree-arrows .bbit-tree-ec-over .bbit-tree-elbow-minus{     background-position:-48px 0; }   .bbit-tree-arrows .bbit-tree-ec-over .bbit-tree-elbow-end-plus{     background-position:-32px 0; }   .bbit-tree-arrows .bbit-tree-ec-over .bbit-tree-elbow-end-minus{     background-position:-48px 0; }   .bbit-tree-elbow-plus, .bbit-tree-elbow-minus, .bbit-tree-elbow-end-plus, .bbit-tree-elbow-end-minus{     cursor:pointer; }   .ie ul.bbit-tree-node-ct{     font-size:0;     line-height:0;     zoom:1; }   .bbit-tree-node{     white-space: nowrap; }   .bbit-tree-node-el {     line-height:18px;     cursor:default;    /* cursor:pointer;*/ }   .bbit-tree-node a{     text-decoration:none;     -khtml-user-select:none;     -moz-user-select:none;     -webkit-user-select:ignore;     -kthml-user-focus:normal;     -moz-user-focus:normal;     -moz-outline: 0 none;     outline:0 none; }   .bbit-tree-node a span{     text-decoration:none;     padding:1px 3px 1px 2px; }   .bbit-tree-node .bbit-tree-node-disabled .bbit-tree-node-icon{    -moz-opacity: 0.5;    opacity:.5;    filter: alpha(opacity=50); }   .bbit-tree-node .bbit-tree-node-inline-icon{     background:transparent; }   .bbit-tree-node a:hover{     text-decoration:none; }       /* Fix for ie rootVisible:false issue，修正一个IEdebug */ .bbit-tree-root {     zoom:1; }     /***********这里是图标了，可以在这里替换哦*****************/ .bbit-tree-node-expanded .bbit-tree-node-icon{     background-image:url(images/tree/folder-open.gif); }   .bbit-tree-node-leaf .bbit-tree-node-icon{     background-image:url(images/tree/leaf.gif); }   .bbit-tree-node-collapsed .bbit-tree-node-icon{     background-image:url(images/tree/folder.gif); }   .bbit-tree-node-loading .bbit-tree-node-icon{     background-image:url(images/tree/loading.gif) !important; }   .bbit-tree-node .bbit-tree-node-inline-icon {     background-image: none; }   .bbit-tree-node-loading a span{      font-style: italic;      color:#444444; }   .bbit-tree-lines .bbit-tree-elbow{     background-image:url(images/tree/elbow.gif); }   .bbit-tree-lines .bbit-tree-elbow-plus{     background-image:url(images/tree/elbow-plus.gif); }   .bbit-tree-lines .bbit-tree-elbow-minus{     background-image:url(images/tree/elbow-minus.gif); }   .bbit-tree-lines .bbit-tree-elbow-end{     background-image:url(images/tree/elbow-end.gif); }   .bbit-tree-lines .bbit-tree-elbow-end-plus{     background-image:url(images/tree/elbow-end-plus.gif); }   .bbit-tree-lines .bbit-tree-elbow-end-minus{     background-image:url(images/tree/elbow-end-minus.gif); }   .bbit-tree-lines .bbit-tree-elbow-line{     background-image:url(images/tree/elbow-line.gif); }   .bbit-tree-no-lines .bbit-tree-elbow-plus{     background-image:url(images/tree/elbow-plus-nl.gif); }   .bbit-tree-no-lines .bbit-tree-elbow-minus{     background-image:url(images/tree/elbow-minus-nl.gif); }   .bbit-tree-no-lines .bbit-tree-elbow-end-plus{     background-image:url(images/tree/elbow-end-plus-nl.gif); }   .bbit-tree-no-lines .bbit-tree-elbow-end-minus{     background-image:url(images/tree/elbow-end-minus-nl.gif); }   .bbit-tree-arrows .bbit-tree-elbow-plus{     background-image:url(images/tree/arrows.gif); }   .bbit-tree-arrows .bbit-tree-elbow-minus{     background-image:url(images/tree/arrows.gif); }   .bbit-tree-arrows .bbit-tree-elbow-end-plus{     background-image:url(images/tree/arrows.gif); }   .bbit-tree-arrows .bbit-tree-elbow-end-minus{     background-image:url(images/tree/arrows.gif); }   /*TreeNode 选中的Disabled的一些颜色，字体样式*/ .bbit-tree-node{     color:#000;     font: normal 11px arial, tahoma, helvetica, sans-serif; }   .bbit-tree-node a{     color:#000; } .bbit-tree-node a span{     color:#000; } .bbit-tree-node .bbit-tree-node-disabled a span{     color:gray !important; } .bbit-tree-node .bbit-tree-node-over {     background-color: #eee; }   .bbit-tree-node .bbit-tree-selected {     background-color: #d9e8fb; }

上面了树的基本样式外，定义了一个有+号带line的样式和+号不带line的样式

这就是那个+号带line的样式

css中所用到的所有图片

2：确定数据结构

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var menudata = [{     id: "0.1",//唯一的ID即可     text: "Beyondbit UI Demo",     hasChildren: true,     isexpand: true,     complete: true,     ChildNodes: [{         id: "0.1.1",         text: "日期选择",         hasChildren: true,         isexpand: false,         complete: true,         ChildNodes: [{             id: "0.1.1.1",             text: "控件演示",             value: "Testpages/datepickerDemo.htm",             hasChildren: false,             isexpand: false,             complete: true,             ChildNodes: null         },         ...         ]

这样的结构有个好处就数据本身是带层次的，非常利于遍历，在后面的级联关联中会看到

3： 面子做好了那就开始做里子了，编写脚本（Javascript）

我是JQuery得拥护者，所以自然js的框架自然是采用Jquery了

先上个完整代码，再逐一分析

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/**************************************** author:xuanye.wan@gmail.com page:http://xuanye.cnblogs.com/ ***************************************/ (function($) {     $.fn.swapClass = function(c1, c2) {         return this.removeClass(c1).addClass(c2);     }     $.fn.switchClass = function(c1, c2) {         if (this.hasClass(c1)) {             return this.swapClass(c1, c2);         }         else {             return this.swapClass(c2, c1);         }     }     $.fn.treeview = function(settings) {         var dfop =             {                 method: "POST",                 datatype: "json",                 url: false,                 cbiconpath: "/images/icons/",                 icons: ["checkbox_0.gif", "checkbox_1.gif", "checkbox_2.gif"],                 showcheck: false, //是否显示选择                            oncheckboxclick: false, //当checkstate状态变化时所触发的事件，但是不会触发因级联选择而引起的变化                 onnodeclick: false,                 cascadecheck: true,                 data: null,                 clicktoggle: true, //点击节点展开和收缩子节点                 theme: "bbit-tree-arrows" //bbit-tree-lines ,bbit-tree-no-lines,bbit-tree-arrows             }           $.extend(dfop, settings);         var treenodes = dfop.data;         var me = $(this);         var id = me.attr("id");         if (id == null || id == "") {             id = "bbtree" + new Date().getTime();             me.attr("id", id);         }           var html = [];         buildtree(dfop.data, html);         me.addClass("bbit-tree").html(html.join(""));         InitEvent(me);         html = null;         //预加载图片         if (dfop.showcheck) {             for (var i = 0; i < 3; i++) {                 var im = new Image(16,16);                 im.src = dfop.cbiconpath + dfop.icons[i];             }         }         //region         function buildtree(data, ht) {             ht.push("<div class='bbit-tree-bwrap'>"); // Wrap ;             ht.push("<div class='bbit-tree-body'>"); // body ;             ht.push("<ul class='bbit-tree-root ", dfop.theme, "'>"); //root             var l = data.length;             for (var i = 0; i < l; i++) {                 buildnode(data[i], ht, 0, i, i == l - 1);             }             ht.push("</ul>"); // root and;             ht.push("</div>"); // body end;             ht.push("</div>"); // Wrap end;         }         //endregion         function buildnode(nd, ht, deep, path, isend) {             ht.push("<li class='bbit-tree-node'>");             ht.push("<div id='", id, "_", nd.id, "' tpath='", path, "' unselectable='on'");             var cs = [];             cs.push("bbit-tree-node-el");             if (nd.hasChildren) {                 cs.push(nd.isexpand ? "bbit-tree-node-expanded" : "bbit-tree-node-collapsed");             }             else {                 cs.push("bbit-tree-node-leaf");             }             if (nd.classes) { cs.push(nd.classes); }               ht.push(" class='", cs.join(" "), "'>");             //span indent             ht.push("<span class='bbit-tree-node-indent'>");             if (deep == 1) {                 ht.push("<img class='bbit-tree-icon' src='../Themes/Shared/images/s.gif'/>");             }             else if (deep > 1) {                 ht.push("<img class='bbit-tree-icon' src='../Themes/Shared/images/s.gif'/>");                 for (var j = 1; j < deep; j++) {                     ht.push("<img class='bbit-tree-elbow-line' src='../Themes/Shared/images/s.gif'/>");                 }             }             ht.push("</span>");             //img             cs.length = 0;             if (nd.hasChildren) {                 if (nd.isexpand) {                     cs.push(isend ? "bbit-tree-elbow-end-minus" : "bbit-tree-elbow-minus");                 }                 else {                     cs.push(isend ? "bbit-tree-elbow-end-plus" : "bbit-tree-elbow-plus");                 }             }             else {                 cs.push(isend ? "bbit-tree-elbow-end" : "bbit-tree-elbow");             }             ht.push("<img class='bbit-tree-ec-icon ", cs.join(" "), "' src='../Themes/Shared/images/s.gif'/>");             ht.push("<img class='bbit-tree-node-icon' src='../Themes/Shared/images/s.gif'/>");             //checkbox             if (dfop.showcheck && nd.showcheck) {                 if (nd.checkstate == null || nd.checkstate == undefined) {                     nd.checkstate = 0;                 }                 ht.push("<img  id='", id, "_", nd.id, "_cb' class='bbit-tree-node-cb' src='", dfop.cbiconpath, dfop.icons[nd.checkstate], "'/>");             }             //a             ht.push("<a hideFocus class='bbit-tree-node-anchor' tabIndex=1 href='javascript:void(0);'>");             ht.push("<span unselectable='on'>", nd.text, "</span>");             ht.push("</a>");             ht.push("</div>");             //Child             if (nd.hasChildren) {                 if (nd.isexpand) {                     ht.push("<ul  class='bbit-tree-node-ct'  style='z-index: 0; position: static; visibility: visible; top: auto; left: auto;'>");                     if (nd.ChildNodes) {                         var l = nd.ChildNodes.length;                         for (var k = 0; k < l; k++) {                             nd.ChildNodes[k].parent = nd;                             buildnode(nd.ChildNodes[k], ht, deep + 1, path + "." + k, k == l - 1);                         }                     }                     ht.push("</ul>");                 }                 else {                     ht.push("<ul style='display:none;'></ul>");                 }             }             ht.push("</li>");             nd.render = true;         }         function getItem(path) {             var ap = path.split(".");             var t = treenodes;             for (var i = 0; i < ap.length; i++) {                 if (i == 0) {                     t = t[ap[i]];                 }                 else {                     t = t.ChildNodes[ap[i]];                 }             }             return t;         }         function check(item, state, type) {             var pstate = item.checkstate;             if (type == 1) {                 item.checkstate = state;             }             else {// 上溯                 var cs = item.ChildNodes;                 var l = cs.length;                 var ch = true;                 for (var i = 0; i < l; i++) {                     if ((state == 1 && cs[i].checkstate != 1) || state == 0 && cs[i].checkstate != 0) {                         ch = false;                         break;                     }                 }                 if (ch) {                     item.checkstate = state;                 }                 else {                     item.checkstate = 2;                 }             }             //change show                       if (item.render && pstate != item.checkstate) {                 var et = $("#" + id + "_" + item.id + "_cb");                 if (et.length == 1) {                     et.attr("src", dfop.cbiconpath + dfop.icons[item.checkstate]);                 }             }         }         //遍历子节点         function cascade(fn, item, args) {             if (fn(item, args, 1) != false) {                 if (item.ChildNodes != null && item.ChildNodes.length > 0) {                     var cs = item.ChildNodes;                     for (var i = 0, len = cs.length; i < len; i++) {                         cascade(fn, cs[i], args);                     }                 }             }         }         //冒泡的祖先         function bubble(fn, item, args) {             var p = item.parent;             while (p) {                 if (fn(p, args, 0) === false) {                     break;                 }                 p = p.parent;             }         }         function nodeclick(e) {             var path = $(this).attr("tpath");             var et = e.target || e.srcElement;             var item = getItem(path);               //debugger;             if (et.tagName == "IMG") {                 // +号需要展开                 if ($(et).hasClass("bbit-tree-elbow-plus") || $(et).hasClass("bbit-tree-elbow-end-plus")) {                     var ul = $(this).next(); //"bbit-tree-node-ct"                     if (ul.hasClass("bbit-tree-node-ct")) {                         ul.show();                     }                     else {                         var deep = path.split(".").length;                         if (item.complete) {                             item.ChildNodes != null && asnybuild(item.ChildNodes, deep, path, ul, item);                         }                         else {                             $(this).addClass("bbit-tree-node-loading");                             asnyloadc(ul, item, function(data) {                                 item.complete = true;                                 item.ChildNodes = data;                                 asnybuild(data, deep, path, ul, item);                             });                         }                     }                     if ($(et).hasClass("bbit-tree-elbow-plus")) {                         $(et).swapClass("bbit-tree-elbow-plus", "bbit-tree-elbow-minus");                     }                     else {                         $(et).swapClass("bbit-tree-elbow-end-plus", "bbit-tree-elbow-end-minus");                     }                     $(this).swapClass("bbit-tree-node-collapsed", "bbit-tree-node-expanded");                 }                 else if ($(et).hasClass("bbit-tree-elbow-minus") || $(et).hasClass("bbit-tree-elbow-end-minus")) {  //- 号需要收缩                                        $(this).next().hide();                     if ($(et).hasClass("bbit-tree-elbow-minus")) {                         $(et).swapClass("bbit-tree-elbow-minus", "bbit-tree-elbow-plus");                     }                     else {                         $(et).swapClass("bbit-tree-elbow-end-minus", "bbit-tree-elbow-end-plus");                     }                     $(this).swapClass("bbit-tree-node-expanded", "bbit-tree-node-collapsed");                 }                 else if ($(et).hasClass("bbit-tree-node-cb")) // 点击了Checkbox                 {                     var s = item.checkstate != 1 ? 1 : 0;                     var r = true;                     if (dfop.oncheckboxclick) {                         r = dfop.oncheckboxclick.call(et, item, s);                     }                     if (r != false) {                         if (dfop.cascadecheck) {                             //遍历                             cascade(check, item, s);                             //上溯                             bubble(check, item, s);                         }                         else {                             check(item, s, 1);                         }                     }                 }             }             else {                 if (dfop.citem) {                     $("#" + id + "_" + dfop.citem.id).removeClass("bbit-tree-selected");                 }                 dfop.citem = item;                 $(this).addClass("bbit-tree-selected");                 if (dfop.onnodeclick) {                     dfop.onnodeclick.call(this, item);                 }             }         }         function asnybuild(nodes, deep, path, ul, pnode) {             var l = nodes.length;             if (l > 0) {                 var ht = [];                 for (var i = 0; i < l; i++) {                     nodes[i].parent = pnode;                     buildnode(nodes[i], ht, deep, path + "." + i, i == l - 1);                 }                 ul.html(ht.join(""));                 ht = null;                 InitEvent(ul);             }             ul.addClass("bbit-tree-node-ct").css({ "z-index": 0, position: "static", visibility: "visible", top: "auto", left: "auto", display: "" });             ul.prev().removeClass("bbit-tree-node-loading");         }         function asnyloadc(pul, pnode, callback) {             if (dfop.url) {                 var param = builparam(pnode);                 $.ajax({                     type: dfop.method,                     url: dfop.url,                     data: param,                     dataType: dfop.datatype,                     success: callback,                     error: function(e) { alert("error occur!"); }                 });             }         }         function builparam(node) {             var p = [{ name: "id", value: encodeURIComponent(node.id) }                     , { name: "text", value: encodeURIComponent(node.text) }                     , { name: "value", value: encodeURIComponent(node.value) }                     , { name: "checkstate", value: node.checkstate}];             return p;         }         function InitEvent(parent) {             var nodes = $("li.bbit-tree-node>div", parent);             nodes.each(function(e) {                 $(this).hover(function() {                     $(this).addClass("bbit-tree-node-over");                 }, function() {                     $(this).removeClass("bbit-tree-node-over");                 })                 .click(nodeclick)                 .find("img.bbit-tree-ec-icon").each(function(e) {                     if (!$(this).hasClass("bbit-tree-elbow")) {                         $(this).hover(function() {                             $(this).parent().addClass("bbit-tree-ec-over");                         }, function() {                             $(this).parent().removeClass("bbit-tree-ec-over");                         });                     }                 });             });         }         function getck(items, c, fn) {             for (var i = 0, l = items.length; i < l; i++) {                 items[i].checkstate == 1 && c.push(fn(items[i]));                 if (items[i].ChildNodes != null && items[i].ChildNodes.length > 0) {                     getck(items[i].ChildNodes, c, fn);                 }             }         }         me[0].t = {             getSelectedNodes: function() {                 var s = [];                 getck(treenodes, s, function(item) { return item });                 return s;             },             getSelectedValues: function() {                 var s = [];                 getck(treenodes, s, function(item) { return item.value });                 return s;             },             getCurrentItem: function() {                 return dfop.citem;             }         };         return me;     }     //获取所有选中的节点的Value数组     $.fn.getTSVs = function() {         if (this[0].t) {             return this[0].t.getSelectedValues();         }         return null;     }     //获取所有选中的节点的Item数组     $.fn.getTSNs = function() {         if (this[0].t) {             return this[0].t.getSelectedNodes();         }         return null;     }     $.fn.getTCT = function() {         if (this[0].t) {             return this[0].t.getCurrentItem();         }         return null;     }   })(jQuery);

第一步：自然是所有Jquery的控件的第一步都是搭这个架子，兼容JQuery和$避免闭包，避免和其他类库冲突，接受一个参数（是个对象）

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;(function($) {      //也可以使用$.fn.extend(treeview:function(setting){})     $.fn.treeview = function(settings) {     }   })(jQuery);

那第二步：给控件加一些参数默认参数，同时能调用方法$.extend让最终调用时的参数覆盖默认的（如果没有则使用默认）

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var dfop ={                 method: "POST",//默认采用POST提交数据                 datatype: "json",//数据类型是json                 url: false,//异步请求的url                 cbiconpath: "/images/icons/",//checkbox icon的目录位置                 icons: ["checkbox_0.gif", "checkbox_1.gif", "checkbox_2.gif"],//checkbxo三态的图片                 showcheck: false, //是否显示checkbox                          oncheckboxclick: false, //点击checkbox时触发的事件                 onnodeclick: false,//点击node触发的时间                 cascadecheck: true,//是否启用级联                 data: null,//初始化数据                             theme: "bbit-tree-arrows" //三种风格备选bbit-tree-lines ,bbit-tree-no-lines,bbit-tree-arrows             }         //用传进来的参数覆盖默认，没传则保留         $.extend(dfop, settings);

第三步：生成默认数据的HTML（根据我们的分析节点的Dom结构，数据的数据结构，生成节点那是非常的简单），，添加到当前容器中。最后是注册事件这里有一个非常重要的地方，即懒加载(没有展开的节点HTML是不生成的)，这就要求我们在树内部要维护一套数据（开销很小），对于性能的提升那是相当的明显。另外一个重要的地方，就是使用一次生成所有展开节点的HTML并通过innerHTML属性来生成Dom，而不是通过append操作，因为直接操作innerHTML比通过dom原生的方法要快上N倍（节点越多，N越大），切记切记！

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var treenodes = dfop.data; //内部的数据，其实直接用 dfop.data也可以 var me = $(this); var id = me.attr("id"); if (id == null || id == "") {     id = "bbtree" + new Date().getTime();     me.attr("id", id); }//全局唯一的ID   var html = []; buildtree(dfop.data, html);//生成展开节点的HTML，push到数组中 me.addClass("bbit-tree").html(html.join("")); InitEvent(me);//初始化事件 html = null;

在节点生成过程中，同时可生产节点的Path（节点路径），方便检索

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if (nd.hasChildren) { //存在子节点     if (nd.isexpand) {//同时节点已经展开则输出子节点         ht.push("<ul  class='bbit-tree-node-ct'  style='z-index: 0; position: static; visibility: visible; top: auto; left: auto;'>");         if (nd.ChildNodes) {             var l = nd.ChildNodes.length;             for (var k = 0; k < l; k++) {//递归调用并生产节点的路径                 nd.ChildNodes[k].parent = nd;                 buildnode(nd.ChildNodes[k], ht, deep + 1, path + "." + k, k == l - 1);             }         }         ht.push("</ul>");     }     else { //否则是待输出状态         ht.push("<ul style='display:none;'></ul>");     } }

注册事件，接受参数parent，即从某一父节点开始附加事件（因为做了个hover效果，所以事件是在每个节点上，如果取消该效果，事件可直接附加Tree上通过Event的srcElement来分发可略提升性能）

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function InitEvent(parent) {           var nodes = $("li.bbit-tree-node>div", parent);           nodes.each(function(e) {               $(this).hover(function() {                   $(this).addClass("bbit-tree-node-over"); //鼠标浮动节点的样式变化               }, function() {                   $(this).removeClass("bbit-tree-node-over");               })               .click(nodeclick)//node的onclick事件，这个是重点哦               .find("img.bbit-tree-ec-icon").each(function(e) { //arrow的hover事件，为了实现vista那个风格的                   if (!$(this).hasClass("bbit-tree-elbow")) {                       $(this).hover(function() {                           $(this).parent().addClass("bbit-tree-ec-over");                       }, function() {                           $(this).parent().removeClass("bbit-tree-ec-over");                       });                   }               });           }); }

这里最主要的还是node的click事件，因为他要处理的事情很多，如树的展开收缩（如果子节点不存在，但是hasChildren为真，同时complete属性不为真则需要异步加载子节点，如子节点存在，但是没有Render那么就要Render）,点击checkbox要出发级联的事件和oncheckbox事件，点击其他则触发配置条件的nodeonclick事件，这一切都通过前面event的源元素的class来区分点击的对象

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function nodeclick(e) {     var path = $(this).attr("tpath");//获取节点路径     var et = e.target || e.srcElement;//获取事件源     var item = getItem(path);//根据path获取节点的数据     //debugger;     if (et.tagName == "IMG") {         // +号需要展开，处理加减号         if ($(et).hasClass("bbit-tree-elbow-plus") || $(et).hasClass("bbit-tree-elbow-end-plus")) {             var ul = $(this).next(); //"bbit-tree-node-ct"             if (ul.hasClass("bbit-tree-node-ct")) {                 ul.show();             }             else {                 var deep = path.split(".").length;                 if (item.complete) {                     item.ChildNodes != null && asnybuild(item.ChildNodes, deep, path, ul, item);                 }                 else {                     $(this).addClass("bbit-tree-node-loading");                     asnyloadc(ul, item, function(data) {                         item.complete = true;                         item.ChildNodes = data;                         asnybuild(data, deep, path, ul, item);                     });                 }             }             if ($(et).hasClass("bbit-tree-elbow-plus")) {                 $(et).swapClass("bbit-tree-elbow-plus", "bbit-tree-elbow-minus");             }             else {                 $(et).swapClass("bbit-tree-elbow-end-plus", "bbit-tree-elbow-end-minus");             }             $(this).swapClass("bbit-tree-node-collapsed", "bbit-tree-node-expanded");         }         else if ($(et).hasClass("bbit-tree-elbow-minus") || $(et).hasClass("bbit-tree-elbow-end-minus")) {  //- 号需要收缩                                $(this).next().hide();             if ($(et).hasClass("bbit-tree-elbow-minus")) {                 $(et).swapClass("bbit-tree-elbow-minus", "bbit-tree-elbow-plus");             }             else {                 $(et).swapClass("bbit-tree-elbow-end-minus", "bbit-tree-elbow-end-plus");             }             $(this).swapClass("bbit-tree-node-expanded", "bbit-tree-node-collapsed");         }         else if ($(et).hasClass("bbit-tree-node-cb")) // 点击了Checkbox         {             var s = item.checkstate != 1 ? 1 : 0;             var r = true;             if (dfop.oncheckboxclick) { //触发配置的函数                 r = dfop.oncheckboxclick.call(et, item, s);             }             if (r != false) {//如果返回值不为false，即checkbxo变化有效                 if (dfop.cascadecheck) {//允许触发级联                     //遍历                     cascade(check, item, s);//则向下关联                     //上溯                     bubble(check, item, s); //向上关联                 }                 else {                     check(item, s, 1);//否则只管自己                 }             }         }     }     else {//点击到了其他地方         if (dfop.citem) { //上一个当前节点             $("#" + id + "_" + dfop.citem.id).removeClass("bbit-tree-selected");         }         dfop.citem = item;//这次的当前节点         $(this).addClass("bbit-tree-selected");         if (dfop.onnodeclick) {             dfop.onnodeclick.call(this, item);         }     } }

展开节点，异步请求的部分代码应该不是很复杂就不细诉了，关键来讲一下级联

级联有两个问题要处理，第一个是遍历子节点，第二个是上溯到祖节点，因为我们的数据结构这两个操作都显得非常简单

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//遍历子节点 function cascade(fn, item, args) {     if (fn(item, args, 1) != false) {         if (item.ChildNodes != null && item.ChildNodes.length > 0) {             var cs = item.ChildNodes;             for (var i = 0, len = cs.length; i < len; i++) {                 cascade(fn, cs[i], args);             }         }     } } //冒泡的祖先 function bubble(fn, item, args) {     var p = item.parent;     while (p) {         if (fn(p, args, 0) === false) {             break;         }         p = p.parent;     } }

找到节点的同时都会触发check这个回调函数，来判断当前节点的状态，详细请看下面代码中的注释部分应该是比较清晰，描写了这个过程

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function check(item, state, type) {     var pstate = item.checkstate; //当前状态     if (type == 1) {         item.checkstate = state; //如果是遍历子节点，父是什么子就是什么     }     else {// 上溯 ，这个就复杂一些了         var cs = item.ChildNodes; //获取当前节点的所有子节点         var l = cs.length;         var ch = true; //是否不是中间状态 半选         for (var i = 0; i < l; i++) {             if ((state == 1 && cs[i].checkstate != 1) || state == 0 && cs[i].checkstate != 0) {                 ch = false;                 break;//他的子节点只要有一个没选中，那么他就是半选             }         }         if (ch) {             item.checkstate = state;//不是半选，则子节点是什么他就是什么         }         else {             item.checkstate = 2; //半选         }     }     //change show 如果节点已输出，而其前后状态不一样，则变化checkbxo的显示             if (item.render && pstate != item.checkstate) {         var et = $("#" + id + "_" + item.id + "_cb");         if (et.length == 1) {             et.attr("src", dfop.cbiconpath + dfop.icons[item.checkstate]);         }     } }

至此我们树的主体功能已经完全实现了。其他就是公开一些方法等，大家可详见代码，示例中公开了两个一个当前选中的所有节点，另外一个当前的节点。

大家可以通过以下网址查看文中的示例，selected拼错了，大家海涵！ windows azure部署还是麻烦懒得修改了3500+节点一次加载，大家可以点击根节点的全选来看看速度

http://jscs.cloudapp.net/ControlsSample/BigTreeSample

异步加载，按需加载的情况也是非常常用的，使用的是SQL Azure服务器在美国ing，所以可能异步有点慢，本地数据源那是瞬间的

http://jscs.cloudapp.net/ControlsSample/TreeAsnySample

FAQ：

1：如何设置每个节点不同的图标？

回答：

其实不用扩展，本身就支持，只是没有说明而已，我们来看一下这个代码吧？在BuildNode方法中有这么一句？      
if (nd.classes) { cs.push(nd.classes); }

在节点的数据结构中可以设置属性classes ，该属性将作为节点特殊的Css Class 添加到节点上。那么利用这点，就可以设置节点的图标了

然后就是编写一个Style 即可

最后来看下效果吧？

出处：http://www.cnblogs.com/xuanye/archive/2009/10/26/xjplugin_jquery_tree.html

demo下载地址： demo