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JQuery日记 5.31 JQuery对象的生成

作者:dayu

init = jQuery.fn.init = function( selector, context ) { var match, elem; // HANDLE: $(""), $(null), $(undefined), $(false) // 返回空JQuery对象 if ( !selector ) { return this; } // Handle HTML strings if ( typeof selector === "string" ) { // 假设selector以'<'开头以'>'结尾而且长度大于3觉得其是HTML字符串,不进行rquickExpr匹配 if ( selector[0] === "<" && selector[ selector.length - 1 ] === ">" && selector.length >= 3 ) { // Assume that strings that start and end with <> are HTML and skip the regex check match = [ null, selector, null ]; } else { match = rquickExpr.exec( selector ); } // Match html or make sure no context is specified for #id if ( match && (match[1] || !context) ) { // HANDLE: $(html) -> $(array) if ( match[1] ) { // 假设context是jquery对象,取第一个DOM元素 context = context instanceof jQuery ? context[0] : context; // scripts is true for back-compat // Intentionally let the error be thrown if parseHTML is not present // 将HTML转换后的DOM元素合并当到当前jquery对象 jQuery.merge( this, jQuery.parseHTML( match[1], context && context.nodeType ? context.ownerDocument || context : document, true ) ); // HANDLE: $(html, props) // 处理第一个參数为HTML字符串第二个參数为JS对象 if ( rsingleTag.test( match[1] ) && jQuery.isPlainObject( context ) ) { // for-each context中元素 for ( match in context ) { // Properties of context are called as methods if possible // 假设当前JQuery对象match属性是函数 if ( jQuery.isFunction( this[ match ] ) ) { // 运行match函数 this[ match ]( context[ match ] ); // ...and otherwise set as attributes // 否则,设置HTML属性 } else { this.attr( match, context[ match ] ); } } } return this; // HANDLE: $(#id) } else { elem = document.getElementById( match[2] ); // Check parentNode to catch when Blackberry 4.6 returns // nodes that are no longer in the document #6963 // Blackberry 4.6缓存过度,不在document中的node仍然查找的到 if ( elem && elem.parentNode ) { // Inject the element directly into the jQuery object this.length = 1; this[0] = elem; } // 设置上下文对象为document this.context = document; this.selector = selector; return this; } // HANDLE: $(expr, $(...)) // 处理没有context參数或context參数是JQuery对象 } else if ( !context || context.jquery ) { // 假设没有context參数则在document范围内调用find方法查找 // 假设有context參数则在本context范围内查找 return ( context || rootjQuery ).find( selector ); // HANDLE: $(expr, context) // (which is just equivalent to: $(context).find(expr) // 处理selector为expr,第二个參数也为context的selector的情况 } else { // 对context进行选择再find return this.constructor( context ).find( selector ); } // HANDLE: $(DOMElement) // 将DOM元素包裹为JQuery对象 } else if ( selector.nodeType ) { this.context = this[0] = selector; this.length = 1; return this; // HANDLE: $(function) // Shortcut for document ready // 假设selector是function // 将function绑定为ready监听,或马上运行(rootjQuery.ready === "undefined") } else if ( jQuery.isFunction( selector ) ) { return typeof rootjQuery.ready !== "undefined" ? rootjQuery.ready( selector ) : // Execute immediately if ready is not present selector( jQuery ); } // 假设selctor是函数或对象时。且有selector元素时 if ( selector.selector !== undefined ) { this.selector = selector.selector; this.context = selector.context; } // 将selector放入当前JQuery对象的数组里 return jQuery.makeArray( selector, this ); };




JQuery日记 5.31 JQuery对象的生成

原文地址:http://www.cnblogs.com/wzzkaifa/p/7217106.html