Ajax中XmlHttpRequest实例笔记

/* * jQuery - New Wave Javascript * * Copyright (c) 2006 John Resig (jquery.com) * Dual licensed under the MIT (MIT-LICENSE.txt) * and GPL (GPL-LICENSE.txt) licenses. * * $Date: 2006-09-07 10:12:12 +0200 (Do, 07 Sep 2006) $ * $Rev: 276 $ */ // Global undefined variable window.undefined = window.undefined; /** * Create a new jQuery Object * * @test ok( Array.prototype.push, "Array.push()" ); * @test ok( Function.prototype.apply, "Function.apply()" ); * @test ok( document.getElementById, "getElementById" ); * @test ok( document.getElementsByTagName, "getElementsByTagName" ); * @test ok( RegExp, "RegExp" ); * @test ok( jQuery, "jQuery" ); * @test ok( $, "$()" ); * * @constructor * @private * @name jQuery * @cat Core */ function jQuery(a,c) { // Shortcut for document ready (because $(document).each() is silly) if ( a && a.constructor == Function && jQuery.fn.ready ) return jQuery(document).ready(a); // Make sure that a selection was provided a = a || jQuery.context || document; // Watch for when a jQuery object is passed as the selector if ( a.jquery ) return jQuery( jQuery.merge( a, [] ) ); // Watch for when a jQuery object is passed at the context if ( c && c.jquery ) return jQuery( c ).find(a); // If the context is global, return a new object if ( window == this ) return new jQuery(a,c); // Handle HTML strings var m = /^[^<]*(<.+>)[^>]*$/.exec(a); if ( m ) a = jQuery.clean( [ m[1] ] ); // Watch for when an array is passed in this.get( a.constructor == Array || a.length && !a.nodeType && a[0] != undefined && a[0].nodeType ? // Assume that it is an array of DOM Elements jQuery.merge( a, [] ) : // Find the matching elements and save them for later jQuery.find( a, c ) ); // See if an extra function was provided var fn = arguments[ arguments.length - 1 ]; // If so, execute it in context if ( fn && fn.constructor == Function ) this.each(fn); } // Map over the $ in case of overwrite if ( typeof $ != "undefined" ) jQuery._$ = $; /** * This function accepts a string containing a CSS selector, * basic XPath, or raw HTML, which is then used to match a set of elements. * The HTML string is different from the traditional selectors in that * it creates the DOM elements representing that HTML string, on the fly, * to be (assumedly) inserted into the document later. * * The core functionality of jQuery centers around this function. * Everything in jQuery is based upon this, or uses this in some way. * The most basic use of this function is to pass in an expression * (usually consisting of CSS or XPath), which then finds all matching * elements and remembers them for later use. * * By default, $() looks for DOM elements within the context of the * current HTML document. * * @example $("div > p") * @desc This finds all p elements that are children of a div element. * @before <p>one</p> <div><p>two</p></div> <p>three</p> * @result [ <p>two</p> ] * * @example $("<div><p>Hello</p></div>").appendTo("#body") * @desc Creates a div element (and all of its contents) dynamically, and appends it to the element with the ID of body. * * @name $ * @param String expr An expression to search with, or a string of HTML to create on the fly. * @cat Core * @type jQuery */ /** * This function accepts a string containing a CSS selector, or * basic XPath, which is then used to match a set of elements with the * context of the specified DOM element, or document * * @example $("div", xml.responseXML) * @desc This finds all div elements within the specified XML document. * * @name $ * @param String expr An expression to search with. * @param Element context A DOM Element, or Document, representing the base context. * @cat Core * @type jQuery */ /** * Wrap jQuery functionality around a specific DOM Element. * This function also accepts XML Documents and Window objects * as valid arguments (even though they are not DOM Elements). * * @example $(document).find("div > p") * @before <p>one</p> <div><p>two</p></div> <p>three</p> * @result [ <p>two</p> ] * * @example $(document.body).background( "black" ); * @desc Sets the background color of the page to black. * * @name $ * @param Element elem A DOM element to be encapsulated by a jQuery object. * @cat Core * @type jQuery */ /** * Wrap jQuery functionality around a set of DOM Elements. * * @example $( myForm.elements ).hide() * @desc Hides all the input elements within a form * * @name $ * @param Array<Element> elems An array of DOM elements to be encapsulated by a jQuery object. * @cat Core * @type jQuery */ /** * A shorthand for $(document).ready(), allowing you to bind a function * to be executed when the DOM document has finished loading. This function * behaves just like $(document).ready(), in that it should be used to wrap * all of the other $() operations on your page. While this function is, * technically, chainable - there really isn't much use for chaining against it. * * @example $(function(){ * // Document is ready * }); * @desc Executes the function when the DOM is ready to be used. * * @name $ * @param Function fn The function to execute when the DOM is ready. * @cat Core * @type jQuery */ /** * A means of creating a cloned copy of a jQuery object. This function * copies the set of matched elements from one jQuery object and creates * another, new, jQuery object containing the same elements. * * @example var div = $("div"); * $( div ).find("p"); * @desc Locates all p elements with all div elements, without disrupting the original jQuery object contained in 'div' (as would normally be the case if a simple div.find("p") was done). * * @name $ * @param jQuery obj The jQuery object to be cloned. * @cat Core * @type jQuery */ // Map the jQuery namespace to the '$' one var $ = jQuery; jQuery.fn = jQuery.prototype = { /** * The current SVN version of jQuery. * * @private * @property * @name jquery * @type String * @cat Core */ jquery: "$Rev: 276 $", /** * The number of elements currently matched. * * @example $("img").length; * @before <img src="test1.jpg"/> <img src="test2.jpg"/> * @result 2 * * @test cmpOK( $("div").length, "==", 2, "Get Number of Elements Found" ); * * @property * @name length * @type Number * @cat Core */ /** * The number of elements currently matched. * * @example $("img").size(); * @before <img src="test1.jpg"/> <img src="test2.jpg"/> * @result 2 * * @test cmpOK( $("div").size(), "==", 2, "Get Number of Elements Found" ); * * @name size * @type Number * @cat Core */ size: function() { return this.length; }, /** * Access all matched elements. This serves as a backwards-compatible * way of accessing all matched elements (other than the jQuery object * itself, which is, in fact, an array of elements). * * @example $("img").get(); * @before <img src="test1.jpg"/> <img src="test2.jpg"/> * @result [ <img src="test1.jpg"/> <img src="test2.jpg"/> ] * * @test isSet( $("div").get(), q("main","foo"), "Get All Elements" ); * * @name get * @type Array<Element> * @cat Core */ /** * Access a single matched element. num is used to access the * Nth element matched. * * @example $("img").get(1); * @before <img src="test1.jpg"/> <img src="test2.jpg"/> * @result [ <img src="test1.jpg"/> ] * * @test cmpOK( $("div").get(0), "==", document.getElementById("main"), "Get A Single Element" ); * * @name get * @type Element * @param Number num Access the element in the Nth position. * @cat Core */ /** * Set the jQuery object to an array of elements. * * @example $("img").get([ document.body ]); * @result $("img").get() == [ document.body ] * * @private * @name get * @type jQuery * @param Elements elems An array of elements * @cat Core */ get: function( num ) { // Watch for when an array (of elements) is p