jQuery源码学习笔记二 转

<p>前文提要，jQuery用init方法创建的，它是jQuery.fn.init的实例而非jQuery的实例，后期会用jQuery.fn.init.<wbr>prototype =<wbr> <wbr>jQuery.fn;把相应的能力从jQuery.prototype搬运到jQuery.fn.init.prototype上。因此，init之后，作者就放心地往jQuery的原型添加方法。而这些原型更多的时候是往外调用其静态方法来工作。一开始，都是一些用于构建类数组的东西。像setArray,makeArray,size,get,pushStack等方法。</p>

<pre class="brush:javascript;gutter:false;toolbar:false">
//&#64;author  司徒正美|なさみ|cheng http://www.cnblogs.com/rubylouvre/  All rights reserved
     //另一个复杂的方法
	css: function( key, value ) {
		// ignore negative width and height values
		if ( (key == 'width' || key == 'height') && parseFloat(value) &lt; 0 )
			value = undefined;
		return this.attr( key, value, "curCSS" );
	},
   //与css与attr一样，既能读亦能写
	text: function( text ) {
		if ( typeof text !== "object" && text != null )
			return this.empty().append( (this[0] && this[0].ownerDocument || document).createTextNode( text ) );

		var ret = "";

		jQuery.each( text || this, function(){
			jQuery.each( this.childNodes, function(){
				if ( this.nodeType != 8 )
					ret += this.nodeType != 1 ?
						this.nodeValue :
						jQuery.fn.text( [ this ] );
			});
		});

		return ret;
	},

    //把匹配的元素作出了为一个整体用参数里的标签（如果传入的是元素也会转换为标签）包起来,
    //$("p").wrapAll('&lt;div&gt;&lt;/div&gt;') =&gt;  &lt;div&gt;&lt;p&gt;******&lt;/p&gt;&lt;p&gt;******&lt;/p&gt;&lt;p&gt;******&lt;/p&gt;&lt;/div&gt;

    //这东西应该叫wrapOutter更好
	wrapAll: function( html ) {
		if ( this[0] ) {
			// The elements to wrap the target around
			var wrap = jQuery( html, this[0].ownerDocument ).clone();

			if ( this[0].parentNode )
				wrap.insertBefore( this[0] );

			wrap.map(function(){
				var elem = this;

				while ( elem.firstChild )
					elem = elem.firstChild;

				return elem;
			}).append(this);
		}

		return this;
	},
    //相当于把匹配的元素取得其innerHTML，然后用wrapAll方法包起来
    //$("p").wrapInner('&lt;div&gt;&lt;/div&gt;') =&gt;  &lt;p&gt;&lt;div&gt;******&lt;/div&gt;&lt;/p&gt;&lt;p&gt;&lt;div&gt;******&lt;/div&gt;&lt;/p&gt;&lt;p&gt;&lt;div&gt;******&lt;/div&gt;&lt;/p&gt;

   wrapInner: function( html ) {
		return this.each(function(){
			jQuery( this ).contents().wrapAll( html );
		});
	},
//与上面相反，有点像outterHTML，内容外面加一层皮
//$("p").wrap('&lt;div&gt;&lt;/div&gt;') =&gt;  &lt;div&gt;&lt;p&gt;******&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;p&gt;******&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;p&gt;******&lt;/p&gt;&lt;/div&gt;

	wrap: function( html ) {
		return this.each(function(){
			jQuery( this ).wrapAll( html );
		});
	},
</pre>
<p>接着下来分析append，prepend，before，after。内部实现非常复杂，先扼要类比一下已有的API吧。</p>
<pre class="brush:javascript;gutter:false;toolbar:false">
//append:向每个匹配的元素内部追加内容。
//相当于
//insertAdjacentHTML("beforeEnd",htmlstr)
//insertAdjacentElement("beforeEnd",dom)
//insertAdjacentElement("beforeEnd",jQueryEl)
//并且具有处理复数个DOM对象的能力（内部用jQuery.each实现）
</pre>
<pre class="brush:javascript;gutter:false;toolbar:false">
//prepend:向每个匹配的元素内部前置内容。
//相当于
//insertAdjacentHTML("afterBegin",htmlstr)
//insertAdjacentElement("afterBegin",dom)
//insertAdjacentElement("afterBegin",jQueryEl)
//并且具有处理复数个DOM对象的能力（内部用jQuery.each实现）
</pre>
<pre class="brush:javascript;gutter:false;toolbar:false">
//before:在每个匹配的元素之前插入内容。
//相当于
//insertAdjacentHTML("beforeBegin",htmlstr)
//insertAdjacentElement("beforeBegin",dom)
//insertAdjacentElement("beforeBegin",jQueryEl)
//并且具有处理复数个DOM对象的能力（内部用jQuery.each实现）
</pre>
<pre class="brush:javascript;gutter:false;toolbar:false">
//after:在每个匹配的元素之后插入内容。。
//相当于
//insertAdjacentHTML("afterEnd",htmlstr)
//insertAdjacentElement("afterEnd",dom)
//insertAdjacentElement("afterEnd",jQueryEl)
//并且具有处理复数个DOM对象的能力（内部用jQuery.each实现）
</pre>

<p>这些方法内部都调用一个叫domManip的方法，它的存在价值仅仅是为了兼容邪恶的火狐，因为火狐死活不支持IE的insertAdjacentXXX系列。</p>
<pre class="brush:javascript;gutter:false;toolbar:false">
//&#64;author  司徒正美|なさみ|cheng http://www.cnblogs.com/rubylouvre/  All rights reserved
//主要用于返回上次覆盖了DOM元素数组
      end: function() {
        return this.prevObject || jQuery( [] );
      },
      
      // For internal use only.
      // Behaves like an Array's method, not like a jQuery method.
      push: [].push,
      sort: [].sort,
      splice: [].splice,
      //jQuery强大的CSS选择器
      find: function( selector ) {
        if ( this.length === 1 ) {
          var ret = this.pushStack( [], "find", selector );
          ret.length = 0;
          //分别为表达式，上下文，与之前获得的元素集合（它们将作为此次的搜索起点）
          jQuery.find( selector, this[0], ret );
          return ret;
        } else {
          //每次都会重新洗牌，因此必须进行压栈操作
          return this.pushStack( jQuery.unique(jQuery.map(this, function(elem){
            return jQuery.find( selector, elem );
          })), "find", selector );
        }
      },
      //先复制DOM再复制其上的事件
      clone: function( events ) {
        // Do the clone
        var ret = this.map(function(){
          if ( !jQuery.support.noCloneEvent && !jQuery.isXMLDoc(this) ) {
            // IE copies events bound via attachEvent when
            // using cloneNode. Calling detachEvent on the
            // clone will also remove the events from the orignal
            // In order to get around this, we use innerHTML.
            // Unfortunately, this means some modifications to
            // attributes in IE that are actually only stored
            // as properties will not be copied (such as the
            // the name attribute on an input).
            var html = this.outerHTML;
            
            if ( !html ) {
              var div = this.ownerDocument.createElement("div");
              div.appendChild( this.cloneNode(true) );
              html = div.innerHTML;
            }
            //将字符串转换成jQuery对象
            return jQuery.clean([html.replace(/ jQuery\d+="(?:\d+|null)"/g, "").replace(/^\s*/, "")])[0];
          } else
            return this.cloneNode(true);
        });
        //许多是后面的方法，到时再说
        // Copy the events from the original to the clone
        if ( events === true ) {
          var orig = this.find("*").andSelf(), i = 0;
          
          ret.find("*").andSelf().each(function(){
            if ( this.nodeName !== orig[i].nodeName )
              return;
            
            var events = jQuery.data( orig[i], "events" );
            
            for ( var type in events ) {
              for ( var handler in events[ type ] ) {
                jQuery.event.add( this, type, events[ type ][ handler ], events[ type ][ handler ].data );
              }
            }
            
            i++;
          });
        }
        
        // Return the cloned set
        return ret;
      },
      //如果参数是函数则用jQuery.greg，否则用jQuery.multiFiler
      filter: function( selector ) {
        return this.pushStack(
        jQuery.isFunction( selector ) &&
          jQuery.grep(this, function(elem, i){
          return selector.call( elem, i );
        }) ||
          
          jQuery.multiFilter( selector, jQuery.grep(this, function(elem){
          return elem.nodeType === 1;
        }) ), "filter", selector );
      },
      //筛选最近的元素
      closest: function( selector ) {
        //判断是否用于方位的
        var pos = jQuery.expr.match.POS.test( selector ) ? jQuery(selector) : null,
        closer = 0;
        //把得到元素用map进行进一步的筛选
        return this.map(function(){
          var cur = this;
          while ( cur && cur.ownerDocument ) {
            if ( pos ? pos.index(cur) &gt; -1 : jQuery(cur).is(selector) ) {
              jQuery.data(cur, "closest", closer);
              return cur;
            }
            cur = cur.parentNode;
            closer++;
          }
        });
      },
      //用于反选，内部调用filter
      not: function( selector ) {
        if ( typeof selector === "string" )
        // test special case where just one selector is passed in
          if ( isSimple.test( selector ) )//如果单一的类
            return this.pushStack( jQuery.multiFilter( selector, this, true ), "not", selector );
        else
          selector = jQuery.multiFilter( selector, this );
        //处理NodeList
        var isArrayLike = selector.length && selector[selector.length - 1] !== undefined && !selector.nodeType;
        return this.filter(function() {//再回调用filter
          return isArrayLike ? jQuery.inArray( this, selector ) &lt; 0 : this != selector;
        });
      },
      //添加新元素，内部进行清零压栈等操作
      add: function( selector ) {
        return this.pushStack( jQuery.unique( jQuery.merge(
        this.get(),
        typeof selector === "string" ?
          jQuery( selector ) :
          jQuery.makeArray( selector )
      )));
      },
      //相当于javascript1.6 Array的some方法
      is: function( selector ) {
        return !!selector && jQuery.multiFilter( selector, this ).length &gt; 0;
      },
      //怎么这方法那么笨重？！
      hasClass: function( selector ) {
        return !!selector && this.is( "." + selector );
      },
      //基本上是用于获取元素value属性的值
      //对于下拉开框，则是其innerText
      //与css,attr一样，可读可写
      val: function( value ) {
        if ( value === undefined ) {			
          var elem = this[0];
          
          if ( elem ) {
            if( jQuery.nodeName( elem, 'option' ) )
              return (elem.attributes.value || {}).specified ? elem.value : elem.text;
            
            // We need to handle select boxes special
            if ( jQuery.nodeName( elem, "select" ) ) {
              var index = elem.selectedIndex,
              values = [],
              options = elem.options,
              one = elem.type == "select-one";
              
              // Nothing was selected
              if ( index &lt; 0 )
                return null;
              
              // Loop through all the selected options
              for ( var i = one ? index : 0, max = one ? index + 1 : options.length; i &lt; max; i++ ) {
                var option = options[ i ];
                
                if ( option.selected ) {
                  // Get the specifc value for the option
                  value = jQuery(option).val();
                  
                  // We don't need an array for one selects
                  if ( one )
                    return value;
                  
                  // Multi-Selects return an array
                  values.push( value );
                }
              }
              
              return values;				
            }
            
            // Everything else, we just grab the value
            return (elem.value || "").replace(/\r/g, "");
            
          }
          
          return undefined;
        }
        
        if ( typeof value === "number" )
          value += '';
        
        return this.each(function(){
          if ( this.nodeType != 1 )
            return;
          //处理radio的checkbox checked属性，用于返回true与false
          if ( jQuery.isArray(value) && /radio|checkbox/.test( this.type ) )
            this.checked = (jQuery.inArray(this.value, value) &gt;= 0 ||
            jQuery.inArray(this.name, value) &gt;= 0);
          
          else if ( jQuery.nodeName( this, "select" ) ) {
            var values = jQuery.makeArray(value);
            
            jQuery( "option", this ).each(function(){
              this.selected = (jQuery.inArray( this.value, values ) &gt;= 0 ||
                jQuery.inArray( this.text, values ) &gt;= 0);
            });
            
            if ( !values.length )
              this.selectedIndex = -1;
            
          } else
            this.value = value;
        });
      },
      //就是innerHTML
      html: function( value ) {
        return value === undefined ?
          (this[0] ?
          this[0].innerHTML.replace(/ jQuery\d+="(?:\d+|null)"/g, "") :
          null) :
          this.empty().append( value );
      },
      //与replaceNode差不多
      replaceWith: function( value ) {
        return this.after( value ).remove();
      },
      //把等于此索引值的DOM对象从jQuery对象中取出
      eq: function( i ) {
        return this.slice( i, +i + 1 );
      },