一段自以为写得不错的JS代码

// expand event:
//        mouseClick            plus/minus
//        rowSelected            row
ctit.treeNode = Class.create({
    initialize:function(element, options) {
        this.element = $(element);
        this.options = options;
        this.eventMouseClick = this.options.mouseClick.bindAsEventListener(this);
        this.eventRowSelected = this.rowSelected.bindAsEventListener(this);
        this._onRequest = false;
        Event.observe(this.element, "click", this.eventMouseClick);
        Event.observe(this.options.row, "dblclick", this.eventMouseClick);
        Event.observe(this.options.row, "click", this.eventRowSelected);
    },
    destroy:function(){
        Event.stopObserving(this.element, "click", this.eventMouseClick);
        Event.stopObserving(this.options.row, "dblclick", this.eventMouseClick);
        Event.stopObserving(this.options.row, "click", this.eventRowSelected);
    },
    rowSelected:function(event){
        var cs = this.options.table.getElementsByClassName(this.options.currentSelectedClass);
        for(var i=0; i<cs.length; i++){
            Element.removeClassName(cs[i], this.options.currentSelectedClass);
            cs[i].style.backgroundColor = '#fff';
        }
        var tds = this.options.row.cells;
        for(var i=0; i<tds.length; i++){
            Element.addClassName(tds[i], this.options.currentSelectedClass);
            tds[i].style.backgroundColor = '#d7e2e8';
        }
    },
    ajaxRequest:function(url, param, onSuccessCallback){
        if(!this._beginRequest()) {
            return;
        }
        if(this._changePlusMinusIcon()){
            param.ajax = true;
            pThis = this;
            new Ajax.Request(url, {
                method: 'post',
                postBody: $H(param).toQueryString(),
                onSuccess: function(o){
                    if(typeof(onSuccessCallback) === 'function'){
                        var ls = o.responseText.evalJSON();
                        onSuccessCallback(ls, pThis.options.tBody, pThis.options.row);
                    }
                }, 
                onFailure: function(o){
                    alert("Connect to server failure.");
                },
                onComplete: function(o){
                    pThis._endRequest();
                },
                evalScripts:false
            });
        }else{
            this._endRequest();
        }
    },
    _changePlusMinusIcon:function(){
        var imgs = this.element.getElementsByTagName('img');
        if(!imgs) return false;

        if(imgs[0].src.indexOf('inactive_img.gif')>0){
            var src = imgs[0].src.replace(/\binactive_img.gif\b/, 'active_img.gif');
            imgs[0].src = src;
            imgs[0].alt = 'Open';
            this._removeItWithChildren();
            return false;
        }else{
            var src = imgs[0].src.replace(/\bactive_img.gif\b/, 'inactive_img.gif');
            imgs[0].src = src;
            imgs[0].alt = 'Close';
            return true;
        }
    },
    _beginRequest:function(){
        if(this._onRequest) return false;
        this._onRequest = true;
        return true;
    },
    _endRequest:function(){
        this._onRequest = false;
    },
    _removeItWithChildren:function(){
        var row = this.options.row;
        var level = this._getLevel(row);
        var tBody = this.options.tBody;
        var i=0;
        while(true){
            var nextRow = row.nextSibling;
            if(isNull(nextRow)) break;
            var pLevel = this._getLevel(nextRow);
            if(pLevel>level){
                tBody.removeChild(nextRow);
            }else{
                break;
            }
        }
    },
    _getLevel:function(row){
        if(!isNull(row)) {
            var o = row.cells[this.options.treeNodeIndex];
            if(o){
                var mtch = o.className.match(/\bcontent_indent([0-9]+)\b/);
                if(mtch && mtch[1]){
                    return parseInt(mtch[1]);
                }
            }
        }
        return 0;
    }
});