jQuery对象初始化传参数形式

今天学习了jQuery对象初始化的传参方式，和大家分享一下：

jQuery对象初始化的传参方式包括：

1.$(DOMElement)

2.$('<h1>...</h1>'),$('#id'),$('.class')传入字符串,这是最常见的形式,这种传参数经常也传入第二个参数context指定上下文,其中context参数可以为$(...),DOMElement

3.$(function(){});<===>$(document).ready(function(){});

4.$({selector:'.class',context:context})<===>$('.class',context)

jQuery.fn=jQuery.prototype={

constructor:jQuery,

init:function(selector,context,rootjQuery){

varmatch,elem,ret,doc;

//处理$(""),$(null),$(undefined),$(false)这几种参数,直接返回this

if(!selector){

returnthis;

}

//当传参selector为DOM结点时,将context置为selector

if(selector.nodeType){

this.context=this[0]=selector;

this.length=1;

returnthis;

}

//HandleHTMLstrings

//当传入的selector参数为字符串时,

if(typeofselector==="string"){

if(selector.charAt(0)==="<"&&selector.charAt(selector.length-1)===">"&&selector.length>=3){

//Assumethatstringsthatstartandendwith<>areHTMLandskiptheregexcheck

match=[null,selector,null];

}else{

match=rquickExpr.exec(selector);

}

//Matchhtmlormakesurenocontextisspecifiedfor#id

if(match&&(match[1]||!context)){

//HANDLE:$(html)->$(array)

if(match[1]){

context=contextinstanceofjQuery?context[0]:context;

doc=(context&&context.nodeType?context.ownerDocument||context:document);

//scriptsistrueforback-compat

selector=jQuery.parseHTML(match[1],doc,true);

if(rsingleTag.test(match[1])&&jQuery.isPlainObject(context)){

this.attr.call(selector,context,true);

}

returnjQuery.merge(this,selector);

//HANDLE:$(#id)

}else{

elem=document.getElementById(match[2]);

//CheckparentNodetocatchwhenBlackberry4.6returns

//nodesthatarenolongerinthedocument#6963

if(elem&&elem.parentNode){

//HandlethecasewhereIEandOperareturnitems

//bynameinsteadofID

if(elem.id!==match[2]){

returnrootjQuery.find(selector);

}

//Otherwise,weinjecttheelementdirectlyintothejQueryobject

this.length=1;

this[0]=elem;

}

this.context=document;

this.selector=selector;

returnthis;

}

//HANDLE:$(expr,$(...))

}elseif(!context||context.jquery){

return(context||rootjQuery).find(selector);

//HANDLE:$(expr,context)

//(whichisjustequivalentto:$(context).find(expr)

}else{

returnthis.constructor(context).find(selector);

}//www.everclub.cn

//HANDLE:$(function)

//Shortcutfordocumentready

//当selector为function时相当于$(document).ready(selector);

}elseif(jQuery.isFunction(selector)){

returnrootjQuery.ready(selector);

}

//当selector参数为{selector:'#id',context:document}之类时,重置属性selector和context

if(selector.selector!==undefined){

this.selector=selector.selector;

this.context=selector.context;

}

returnjQuery.makeArray(selector,this);

}

};