减少DOM数可以加快浏览器的在解析页面过程中DOM Tree和render tree的构建，从而提高页面性能。为此我们可以把页面中那些首屏渲染不可见的部分HTML暂存在textarea中，等完成渲染后再处理这部分HTML来达到这个目的。 要把textarea 中暂存的HTML内容添加到页面中，使用元素的outerHTML属性是最简单方便的了,不过在DOM标准中并没有定义outerHTML，支持的浏览器有IE6+,safari, operal和 Chrome，经测试FF4.0- 中还不支持。所以我们就来实现一个可以跨浏览器的outerHTML。 This is paragraph with a list following it sdfdsdfsd Kibology for all. scriptology for all Javascript.FAQTs.com
outerHTML 就是获取或设置包含元素标签本身在内的html。下面是实现代码：
复制代码 代码如下:
if(typeof HTMLElement !== "undefined" && !("outerHTML" in HTMLElement.prototype)) {
//console.log("defined outerHTML");
HTMLElement.prototype.__defineSetter__("outerHTML",function(str){
var fragment = document.createdocumentFragment();
var div = document.createElement("div");
div.innerHTML = str;
for(var i=0, n = div.childNodes.length; i
}
this.parentNode.replaceChild(fragment, this);
});
//
HTMLElement.prototype.__defineGetter__("outerHTML",function(){
var tag = this.tagName;
var attributes = this.attributes;
var attr = [];
//for(var name in attributes){//遍历原型链上成员
for(var i=0,n = attributes.length; i
attr.push(attributes[i].name + '="' + attributes[i].value + '"');
}
}
return ((!!this.innerHTML) ?
'<' + tag + ' ' + attr.join(' ')+'>'+this.innerHTML+'' :
'<' + tag + ' ' +attr.join(' ')+'/>');
});
}
代码说明：
1 代码中首先条件判断来监测浏览器是否支持outerHTML以避免覆盖浏览器原生的实现。
2 "__defineSetter__"，"__defineGetter__" 是firefox浏览器私有方面。分别定义当设置属性值和获取属性要执行的操作。
3 在"__defineSetter__" "outerHTML"中为了避免插入页面中元素过多导致频繁发生reflow影响性能。使用了文档碎片对象fragment来暂存需要插入页面中DOM元素。
4 在"__defineGetter__" "outerHTML" 中使用元素attributes属性来遍历给元素指定的属性。结合innerHTML返回了包含原属本身在内的html字符串。
测试代码：
复制代码 代码如下:
假设要获取
代码：
复制代码 代码如下:
var _p = document.getElementById('outerID');
_P = _P.cloneNode();
var _DIV = document.createElement();
_DIV.appendChild(_P);
alert(_DIV.innerHTML); 就是P的outerHTML;
firefox没有outerHTML用以下方法解决
复制代码 代码如下:
if(window.HTMLElement) {
HTMLElement.prototype.__defineSetter__("outerHTML",function(sHTML){
var r=this.ownerdocument.createRange();
r.setStartBefore(this);
var df=r.createContextualFragment(sHTML);
this.parentNode.replaceChild(df,this);
return sHTML;
});
HTMLElement.prototype.__defineGetter__("outerHTML",function(){
var attr;
var attrs=this.attributes;
var str="<"+this.tagName.toLowerCase();
for(var i=0;iattr=attrs[i];
if(attr.specified)
str+=" "+attr.name+'="'+attr.value+'"';
}
if(!this.canHaveChildren)
return str+">";
return str+">"+this.innerHTML+"";
});
HTMLElement.prototype.__defineGetter__("canHaveChildren",function(){
switch(this.tagName.toLowerCase()){
case "area":
case "base":
case "basefont":
case "col":
case "frame":
case "hr":
case "img":
case "br":
case "input":
case "isindex":
case "link":
case "meta":
case "param":
return false;
}
return true;
});
}
测试有效.
关于insertAdjacentHTML兼容的解新决办法
复制代码 代码如下:
//---在组件最后插入html代码
function InsertHtm(op,code,isStart){
if(Dvbbs_IsIE5)
op.insertAdjacentHTML(isStart ? "afterbegin" : "afterEnd",code);
else{
var range=op.ownerdocument.createRange();
range.setStartBefore(op);
var fragment = range.createContextualFragment(code);
if(isStart)
op.insertBefore(fragment,op.firstChild);
else
op.appendChild(fragment);
}
}
关于inner/outerHTML在NC6中的参考
DOM level 1 has no methods to allow for insertion of unparsed HTML into the document tree (as IE allows with insertAdjacentHTML or assignment to inner/outerHTML).NN6 (currently in beta as NN6PR3) know supports the .innerHTMLproperty of HTMLElements so that you can read or write the innerHTML of a page element like in IE4+.NN6 also provides a DOM level 2 compliant Range object to which a createContextualFragment('html source string')was added to spare DOM scripters the task of parsing html and creating DOM elements.You create a Range with var range = document.createRange();Then you should set its start point to the element where you want to insert the html for instance var someElement = document.getElementById('elementID'); range.setStartAfter(someElement);Then you create a document fragment from the html source to insert for example var docFrag = range.createContextualFragment('Kibology for all.
Note that the getter/setter feature is experimental and its syntax is subject to change.
All for Kibology.
HTMLElement.prototype.innerHTML setter = function (str) { var r = this.ownerdocument.createRange(); r.selectNodeContents(this); r.deleteContents(); var df = r.createContextualFragment(str); this.appendChild(df); return str;}HTMLElement.prototype.outerHTML setter = function (str) { var r = this.ownerdocument.createRange(); r.setStartBefore(this); var df = r.createContextualFragment(str); this.parentNode.replaceChild(df, this); return str;}
HTMLElement.prototype.innerHTML getter = function () { return getInnerHTML(this);}
function getInnerHTML(node) { var str = ""; for (var i=0; i
function getOuterHTML(node) { var str = ""; switch (node.nodeType) { case 1: // ELEMENT_NODE str += "<" + node.nodeName; for (var i=0; i
case 8: // COMMENT_NODE str += "" break; }
return str;}
var _leafElems = ["IMG", "HR", "BR", "INPUT"];var leafElems = {};for (var i=0; i<_leafElems.length; i++) leafElems[_leafElems[i]] = true;
然后我们可以封成JS引用
if (/Mozilla/5.0/.test(navigator.userAgent)) document.write('
