Moved ajaxSettings.xhr definition together with support.ajax and support.cors determination into ajax/xhr.js.

src/ajax.js

@@ -182,9 +182,6 @@ jQuery.extend({
 		headers: {},
 		crossDomain: null,
 		*/
-		xhr: function() {
-			return new window.XMLHttpRequest();
-		},
 
 		accepts: {
 			xml: "application/xml, text/xml",
@@ -977,33 +974,4 @@ function determineDataType( s , ct , text , xml ) {
 	return response;
 }
 
-/*
- * Create the request object; 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.
- */
-if ( window.ActiveXObject ) {
-	jQuery.ajaxSettings.xhr = function() {
-	if ( window.location.protocol !== "file:" ) {
-		try {
-			return new window.XMLHttpRequest();
-		} catch( xhrError ) {}
-	}
-
-	try {
-		return new window.ActiveXObject("Microsoft.XMLHTTP");
-	} catch( activeError ) {}
-	};
-}
-
-var testXHR = jQuery.ajaxSettings.xhr();
-
-// Does this browser support XHR requests?
-jQuery.support.ajax = !!testXHR;
-
-// Does this browser support crossDomain XHR requests
-jQuery.support.cors = testXHR && "withCredentials" in testXHR;
-
 })( jQuery );

src/ajax/xhr.js

@@ -7,10 +7,53 @@ var // Next active xhr id
 	xhrs = {},
 
 	// #5280: see below
-	xhrUnloadAbortInstalled;
+	xhrUnloadAbortInstalled,
 
+	// XHR used to determine supports properties
+	testXHR;
 
-jQuery.ajaxTransport( function( s , determineDataType ) {
+// Create the request object; Microsoft failed to properly
+// (This is still attached to ajaxSettings for backward compatibility reasons)
+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() {
+		if ( window.location.protocol !== "file:" ) {
+			try {
+				return new window.XMLHttpRequest();
+			} catch( xhrError ) {}
+		}
+
+		try {
+			return new window.ActiveXObject("Microsoft.XMLHTTP");
+		} catch( activeError ) {}
+	} :
+	// For all other browsers, use the standard XMLHttpRequest object
+	function() {
+		return new window.XMLHttpRequest();
+	};
+
+// Test if we can create an xhr object
+try {
+	testXHR = jQuery.ajaxSettings.xhr();
+} catch( xhrCreationException ) {}
+
+//Does this browser support XHR requests?
+jQuery.support.ajax = !!testXHR;
+
+// Does this browser support crossDomain XHR requests
+jQuery.support.cors = testXHR && "withCredentials" in testXHR;
+
+// No need for the temporary xhr anymore
+testXHR = undefined;
+
+// Create transport if the browser can provide an xhr
+if ( jQuery.support.ajax ) {
+	jQuery.ajaxTransport( function( s , determineDataType ) {
 
 		// Cross domain only allowed if supported through XMLHttpRequest
 		if ( ! s.crossDomain || jQuery.support.cors ) {
@@ -178,6 +221,7 @@ jQuery.ajaxTransport( function( s , determineDataType ) {
 				}
 			};
 		}
-});
+	});
+}
 
 })( jQuery );