DomHelper源码分析

Ext.DomHelper = function(){
    var tempTableEl = null;
    var emptyTags = /^(?:br|frame|hr|img|input|link|meta|range|spacer|wbr|area|param|col)$/i;
    var tableRe = /^table|tbody|tr|td$/i;
    
    // build as innerHTML where available
    var createHtml = function(o){
    	
    	//如果是string,直接返回
        if(typeof o == 'string'){
            return o;
        }
        //如果是数组，逐个递归createHtml，串联起来返回。
        var b = "";
        if (Ext.isArray(o)) {
            for (var i = 0, l = o.length; i < l; i++) {
                b += createHtml(o[i]);
            }
            return b;
        }
        //是object,默认的tag:div.
        if(!o.tag){
            o.tag = "div";
        }
        b += "<" + o.tag;
        
        for(var attr in o){
            if(attr == "tag" || attr == "children" || attr == "cn" || attr == "html" || typeof o[attr] == "function") continue;
            
            //处理style 属性
            if(attr == "style"){
                var s = o["style"];
                //如style是函数，就执行取得返回string
                if(typeof s == "function"){
                    s = s.call();
                }
                //如style是string
                if(typeof s == "string"){
                    b += ' style="' + s + '"';
                }
                //如style是object {height:50,width:30}之类的style的属性
                else if(typeof s == "object"){
                    b += ' style="';
                    for(var key in s){
                        if(typeof s[key] != "function"){
                            b += key + ":" + s[key] + ";";
                        }
                    }
                    b += '"';
                }
            }else{
            	//处理cls属性，即class
                if(attr == "cls"){
                    b += ' class="' + o["cls"] + '"';
                }
                //for属性
                else if(attr == "htmlFor"){
                    b += ' for="' + o["htmlFor"] + '"';
                }else{
                	//其它的属性pass to 标签属性中去
                    b += " " + attr + '="' + o[attr] + '"';
                }
            }
        }
        //对于没有内容的标签，如<hr/>
        if(emptyTags.test(o.tag)){
            b += "/>";
        }else{
            b += ">";
            
            //处理子标签
            var cn = o.children || o.cn;
            if(cn){
                b += createHtml(cn);
            }
            //标签中的内容
            else if(o.html){
                b += o.html;
            }
            
            //标签的结束
            b += "</" + o.tag + ">";
        }
        return b;
    };

    // build as dom
    /** @ignore */
    var createDom = function(o, parentNode){
        var el;
        //o是数组 Allow Arrays of siblings to be inserted
        if (Ext.isArray(o)) { 
        	// in one shot using a DocumentFragment
            el = document.createDocumentFragment(); 
            //创建一组兄弟节点
            for(var i = 0, l = o.length; i < l; i++) {
                createDom(o[i], el);
            }
        }
        //o 是string  // Allow a string as a child spec.
        else if (typeof o == "string)") {        
            el = document.createTextNode(o);//创建文本节点
        } 
        //o是object
        else {
            el = document.createElement(o.tag||'div');
            // In IE some elements don't have setAttribute
            var useSet = !!el.setAttribute; 
            for(var attr in o){
                if(attr == "tag" || attr == "children" || attr == "cn" || attr == "html" || attr == "style" || typeof o[attr] == "function") continue;
                //class属性
                if(attr=="cls"){
                    el.className = o["cls"];
                }else{
                	//为dom set 属性
                    if(useSet) el.setAttribute(attr, o[attr]);
                    else el[attr] = o[attr];
                }
            }
            //set Style属性
            Ext.DomHelper.applyStyles(el, o.style);
           
            //create 子节点
            var cn = o.children || o.cn;
            if(cn){
                createDom(cn, el);
            } else if(o.html){
                el.innerHTML = o.html;
            }
        }
        //加到parentNode中
        if(parentNode){
           parentNode.appendChild(el);
        }
        return el;
    };

    //处理IE table的兼容
    //把<table>html</table>、<table><tbody>html</tbody></table>
    //<table><tbody><tr>html></tr></tbody></table>
    //s:start,e:end,h:html
    //<div><table><tbody><tr><td>html</td></tr></tbody></table></div>
    //4:<td>html</td>  3:<tr><td>html</td></tr>    2:<tbody><tr><td>html</td></tr></tbody>
    var ieTable = function(depth, s, h, e){
    	//table EL
        tempTableEl.innerHTML = [s, h, e].join('');
        var i = -1, el = tempTableEl;
        while(++i < depth){
            el = el.firstChild;
        }
        return el;
    };

    // kill repeat to save bytes
    var ts = '<table>',
        te = '</table>',
        tbs = ts+'<tbody>',
        tbe = '</tbody>'+te,
        trs = tbs + '<tr>',
        tre = '</tr>'+tbe;

    /**
     * @ignore
     * Nasty code for IE's broken table implementation
     */
    var insertIntoTable = function(tag, where, el, html){
       //创建tempTableEl
    	if(!tempTableEl){
            tempTableEl = document.createElement('div');
        }
        var node;//插入的元素
        var before = null;//定义插入的位置，在before这个节点之前插入
        if(tag == 'td'){//td
        	//在td内,不需要特殊处理
            if(where == 'afterbegin' || where == 'beforeend'){ // INTO a TD
                return;
            }
            //在td前，该节点之前插入
            if(where == 'beforebegin'){
                before = el;
                el = el.parentNode;
            }
            //在td后，该节点之后插入
            else{
                before = el.nextSibling;
                el = el.parentNode;
            }
            //node是<td>html</td>
            node = ieTable(4, trs, html, tre);
        }
        else if(tag == 'tr'){//tr
        	//tr前
            if(where == 'beforebegin'){
                before = el;
                el = el.parentNode;
                //node：<tr><td>html</td></tr>
                node = ieTable(3, tbs, html, tbe);
            } 
            //tr后
            else if(where == 'afterend'){
                before = el.nextSibling;
                el = el.parentNode;
                  //node：<tr><td>html</td></tr>
                node = ieTable(3, tbs, html, tbe);
            }
            //tr内
            else{ // INTO a TR
                if(where == 'afterbegin'){
                    before = el.firstChild;
                }
                //node是<td>html</td
                node = ieTable(4, trs, html, tre);
            }
        } else if(tag == 'tbody'){//tbody
        	//tbody前
            if(where == 'beforebegin'){
                before = el;
                el = el.parentNode;
                //node是<tbody><tr><td>html</td></tr></tbody>
                node = ieTable(2, ts, html, te);
            } 
            //tbody后
            else if(where == 'afterend'){
                before = el.nextSibling;
                el = el.parentNode;
                //node是<tbody><tr><td>html</td></tr></tbody>
                node = ieTable(2, ts, html, te);
            } else{
                if(where == 'afterbegin'){
                    before = el.firstChild;
                }
                 //node：<tr><td>html</td></tr>
                node = ieTable(3, tbs, html, tbe);
            }
        } else{ // TABLE
        	//不需要特殊处理
            if(where == 'beforebegin' || where == 'afterend'){ // OUTSIDE the table
                return;
            }
            if(where == 'afterbegin'){
                before = el.firstChild;
            }
            //node是<tbody><tr><td>html</td></tr></tbody>
            node = ieTable(2, ts, html, te);
        }
        //el子节点before前插入node节点
        el.insertBefore(node, before);
        return node;
    };


    return {
    /** True to force the use of DOM instead of html fragments @type Boolean */
    useDom : false,

    /**
     * Returns the markup for the passed Element(s) config.
     * @param {Object} o The DOM object spec (and children)
     * @return {String}
     */
    //得到html标签的string
    markup : function(o){
        return createHtml(o);
    },

    /**
     * Applies a style specification to an element.
     * @param {String/HTMLElement} el The element to apply styles to
     * @param {String/Object/Function} styles A style specification string eg "width:100px", or object in the form {width:"100px"}, or
     * a function which returns such a specification.
     */
    //为元素增加style，style可能是string,objcet,function。
    applyStyles : function(el, styles){
        if(styles){
           el = Ext.fly(el);
           //styles是string
           if(typeof styles == "string"){
           	//height:50px; width:30px;
               var re = /\s?([a-z\-]*)\:\s?([^;]*);?/gi;
               var matches;
               //set Style
               while ((matches = re.exec(styles)) != null){
                   el.setStyle(matches[1], matches[2]);
               }
           }
           //styles是object
           else if (typeof styles == "object"){
           	//set style
               for (var style in styles){
                  el.setStyle(style, styles[style]);
               }
           }
          //style是 function
           else if (typeof styles == "function"){
           	//styles.call() 可能返回string,object
                Ext.DomHelper.applyStyles(el, styles.call());
           }
        }
    },

    /**
     * Inserts an HTML fragment into the DOM.
     * @param {String} where Where to insert the html in relation to el - beforeBegin, afterBegin, beforeEnd, afterEnd.
     * @param {HTMLElement} el The context element
     * @param {String} html The HTML fragmenet
     * @return {HTMLElement} The new node
     */
    insertHtml : function(where, el, html){
        where = where.toLowerCase();
        if(el.insertAdjacentHTML){//ie
        	//insert table
            if(tableRe.test(el.tagName)){
                var rs;
                //如果是table前，后，或td之内，由于返回null.所以就不会执行 return rs;
                if(rs = insertIntoTable(el.tagName.toLowerCase(), where, el, html)){
                    return rs;
                }
            }
            //在对应的位置插入html,返回插入的元素
            switch(where){
                case "beforebegin":
                    el.insertAdjacentHTML('BeforeBegin', html);
                    return el.previousSibling;
                case "afterbegin":
                    el.insertAdjacentHTML('AfterBegin', html);
                    return el.firstChild;
                case "beforeend":
                    el.insertAdjacentHTML('BeforeEnd', html);
                    return el.lastChild;
                case "afterend":
                    el.insertAdjacentHTML('AfterEnd', html);
                    return el.nextSibling;
            }
            throw 'Illegal insertion point -> "' + where + '"';
        }
        //其它浏览器
        //先创建元素Dom range对象
        var range = el.ownerDocument.createRange();
        var frag;
        switch(where){
             case "beforebegin":
             //设定range 开始的位置，在 el之前，
                range.setStartBefore(el);
                //不能直接插入html string,要先生成上下文相关的Fragment
                frag = range.createContextualFragment(html);
                //插入
                el.parentNode.insertBefore(frag, el);
                return el.previousSibling;
             case "afterbegin":
               //有元素
                if(el.firstChild){
                	//设定range 开始的位置 ，在el firstChild之前
                	//为insertBefore定位
                    range.setStartBefore(el.firstChild);
                    frag = range.createContextualFragment(html);
                    el.insertBefore(frag, el.firstChild);
                    return el.firstChild;
                }else{
                	//直接用innerHTML
                    el.innerHTML = html;
                    return el.firstChild;
                }
            case "beforeend":
                //有元素
                if(el.lastChild){
                	//设定range 开始的位置，在 el firstChild之后                
                    range.setStartAfter(el.lastChild);
                    frag = range.createContextualFragment(html);
                    el.appendChild(frag);
                    
                    return el.lastChild;
                }else{
                	//直接用innerHTML
                    el.innerHTML = html;
                    return el.lastChild;
                }
            case "afterend":
                //设定range开始的位置，在 el之后
                range.setStartAfter(el);
                frag = range.createContextualFragment(html);
                el.parentNode.insertBefore(frag, el.nextSibling);
                return el.nextSibling;
            }
            throw 'Illegal insertion point -> "' + where + '"';
    },

    /**
     * Creates new DOM element(s) and inserts them before el.
     * @param {Mixed} el The context element
     * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
     * @param {Boolean} returnElement (optional) true to return a Ext.Element
     * @return {HTMLElement/Ext.Element} The new node
     */
    insertBefore : function(el, o, returnElement){
        return this.doInsert(el, o, returnElement, "beforeBegin");
    },

    /**
     * Creates new DOM element(s) and inserts them after el.
     * @param {Mixed} el The context element
     * @param {Object} o The DOM object spec (and children)
     * @param {Boolean} returnElement (optional) true to return a Ext.Element
     * @return {HTMLElement/Ext.Element} The new node
     */
    insertAfter : function(el, o, returnElement){
        return this.doInsert(el, o, returnElement, "afterEnd", "nextSibling");
    },

    /**
     * Creates new DOM element(s) and inserts them as the first child of el.
     * @param {Mixed} el The context element
     * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
     * @param {Boolean} returnElement (optional) true to return a Ext.Element
     * @return {HTMLElement/Ext.Element} The new node
     */
    insertFirst : function(el, o, returnElement){
        return this.doInsert(el, o, returnElement, "afterBegin", "firstChild");
    },

    // private
    doInsert : function(el, o, returnElement, pos, sibling){
        el = Ext.getDom(el);
        var newNode;
        if(this.useDom){
        	//创建Dom
            newNode = createDom(o, null);
            //在指定的地方插入newNode
            (sibling === "firstChild" ? el : el.parentNode).insertBefore(newNode, sibling ? el[sibling] : el);
        }else{
            var html = createHtml(o);
            newNode = this.insertHtml(pos, el, html);
        }
        return returnElement ? Ext.get(newNode, true) : newNode;
    },

    /**
     * Creates new DOM element(s) and appends them to el.
     * @param {Mixed} el The context element
     * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
     * @param {Boolean} returnElement (optional) true to return a Ext.Element
     * @return {HTMLElement/Ext.Element} The new node
     */
    append : function(el, o, returnElement){
        el = Ext.getDom(el);
        var newNode;
        if(this.useDom){
            newNode = createDom(o, null);
            el.appendChild(newNode);
        }else{
            var html = createHtml(o);
            newNode = this.insertHtml("beforeEnd", el, html);
        }
        return returnElement ? Ext.get(newNode, true) : newNode;
    },

    /**
     * Creates new DOM element(s) and overwrites the contents of el with them.
     * @param {Mixed} el The context element
     * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
     * @param {Boolean} returnElement (optional) true to return a Ext.Element
     * @return {HTMLElement/Ext.Element} The new node
     */
    overwrite : function(el, o, returnElement){
        el = Ext.getDom(el);
        //采用innerHTML
        el.innerHTML = createHtml(o);
        return returnElement ? Ext.get(el.firstChild, true) : el.firstChild;
    },

    /**
     * Creates a new Ext.Template from the DOM object spec.
     * @param {Object} o The DOM object spec (and children)
     * @return {Ext.Template} The new template
     */
    createTemplate : function(o){
        var html = createHtml(o);
        return new Ext.Template(html);
    }
    };
}();