jquery1.5+ ajax跨域请求在IE下没反应分析
jquery1.5+重写过ajax代码,增加了跨域判断(自动判断ajax请求的url地址是否和当前访问的页面同源,jquery1.4-版本没有增加跨域判断,所以直接发送ajax请求,这样就和浏览器的安全设置有关了),jquery1.5+如果跨域访问并且不支持跨域请求(这些都是jquery代码自动判断的),就不会发送ajax请求(所以浏览器安全设置被忽略),导致没有触发任何事件,所以jquery1.4+能在ie配置安全区域的通过域访问数据源后可以跨域请求,而jquery1.5+就完全没有反应。
具体可以参考http://code.jquery.com/jquery-1.10.2.js未压缩的源代码中的这些代码,是否支持跨域jquery是通过xhr的withCredentials属性来判断,在IE10-之前的版本都没有实现,所以jquery1.5+版本在ie下都默认xhr对象不支持跨域(不在考虑ie浏览器的安全配置)。
// Functions to create xhrs function createStandardXHR() { try { return new window.XMLHttpRequest(); } catch( e ) {} } function createActiveXHR() { try { return new window.ActiveXObject("Microsoft.XMLHTTP"); } catch( e ) {} } // Create the request object // (This is still attached to ajaxSettings for backward compatibility) jQuery.ajaxSettings.xhr = window.ActiveXObject ? /* Microsoft failed to properly * implement the XMLHttpRequest in IE7 (can't request local files), * so we use the ActiveXObject when it is available * Additionally XMLHttpRequest can be disabled in IE7/IE8 so * we need a fallback. */ function() { return !this.isLocal && createStandardXHR() || createActiveXHR(); } : // For all other browsers, use the standard XMLHttpRequest object createStandardXHR; // Determine support properties xhrSupported = jQuery.ajaxSettings.xhr(); jQuery.support.cors = !!xhrSupported && ( "withCredentials" in xhrSupported ); xhrSupported = jQuery.support.ajax = !!xhrSupported; // Create transport if the browser can provide an xhr if ( xhrSupported ) { jQuery.ajaxTransport(function( s ) { // Cross domain only allowed if supported through XMLHttpRequest if ( !s.crossDomain || jQuery.support.cors ) { var callback; return { send: function( headers, complete ) { // Get a new xhr var handle, i, xhr = s.xhr(); // Open the socket // Passing null username, generates a login popup on Opera (#2865) if ( s.username ) { xhr.open( s.type, s.url, s.async, s.username, s.password ); } else { xhr.open( s.type, s.url, s.async ); } // Apply custom fields if provided if ( s.xhrFields ) { for ( i in s.xhrFields ) { xhr[ i ] = s.xhrFields[ i ]; } } // Override mime type if needed if ( s.mimeType && xhr.overrideMimeType ) { xhr.overrideMimeType( s.mimeType ); } // X-Requested-With header // For cross-domain requests, seeing as conditions for a preflight are // akin to a jigsaw puzzle, we simply never set it to be sure. // (it can always be set on a per-request basis or even using ajaxSetup) // For same-domain requests, won't change header if already provided. if ( !s.crossDomain && !headers["X-Requested-With"] ) { headers["X-Requested-With"] = "XMLHttpRequest"; } // Need an extra try/catch for cross domain requests in Firefox 3 try { for ( i in headers ) { xhr.setRequestHeader( i, headers[ i ] ); } } catch( err ) {} // Do send the request // This may raise an exception which is actually // handled in jQuery.ajax (so no try/catch here) xhr.send( ( s.hasContent && s.data ) || null ); // Listener callback = function( _, isAbort ) { var status, responseHeaders, statusText, responses; // Firefox throws exceptions when accessing properties // of an xhr when a network error occurred // http://helpful.knobs-dials.com/index.php/Component_returned_failure_code:_0x80040111_(NS_ERROR_NOT_AVAILABLE) try { // Was never called and is aborted or complete if ( callback && ( isAbort || xhr.readyState === 4 ) ) { // Only called once callback = undefined; // Do not keep as active anymore if ( handle ) { xhr.onreadystatechange = jQuery.noop; if ( xhrOnUnloadAbort ) { delete xhrCallbacks[ handle ]; } } // If it's an abort if ( isAbort ) { // Abort it manually if needed if ( xhr.readyState !== 4 ) { xhr.abort(); } } else { responses = {}; status = xhr.status; responseHeaders = xhr.getAllResponseHeaders(); // When requesting binary data, IE6-9 will throw an exception // on any attempt to access responseText (#11426) if ( typeof xhr.responseText === "string" ) { responses.text = xhr.responseText; } // Firefox throws an exception when accessing // statusText for faulty cross-domain requests try { statusText = xhr.statusText; } catch( e ) { // We normalize with Webkit giving an empty statusText statusText = ""; } // Filter status for non standard behaviors // If the request is local and we have data: assume a success // (success with no data won't get notified, that's the best we // can do given current implementations) if ( !status && s.isLocal && !s.crossDomain ) { status = responses.text ? 200 : 404; // IE - #1450: sometimes returns 1223 when it should be 204 } else if ( status === 1223 ) { status = 204; } } } } catch( firefoxAccessException ) { if ( !isAbort ) { complete( -1, firefoxAccessException ); } } // Call complete if needed if ( responses ) { complete( status, statusText, responses, responseHeaders ); } }; if ( !s.async ) { // if we're in sync mode we fire the callback callback(); } else if ( xhr.readyState === 4 ) { // (IE6 & IE7) if it's in cache and has been // retrieved directly we need to fire the callback setTimeout( callback ); } else { handle = ++xhrId; if ( xhrOnUnloadAbort ) { // Create the active xhrs callbacks list if needed // and attach the unload handler if ( !xhrCallbacks ) { xhrCallbacks = {}; jQuery( window ).unload( xhrOnUnloadAbort ); } // Add to list of active xhrs callbacks xhrCallbacks[ handle ] = callback; } xhr.onreadystatechange = callback; } }, abort: function() { if ( callback ) { callback( undefined, true ); } } }; } }); }
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