I discovered that IE7 and IE8 throw a javascript error on delete window[callbackId];

nateflink · nateflink · commit f9f43eabe051 · 2011-11-10T15:18:18.000-06:00
diff --git a/src/Browser.js b/src/Browser.js
@@ -110,7 +110,7 @@ function Browser(window, document, body, XHR, $log, $sniffer) {
         } else {
           completeOutstandingRequest(callback);
         }
-        delete window[callbackId];
+        window[callbackId] = null;//IE7 IE8 don't like delete window[callbackId];
         body[0].removeChild(script);
       });
     } else {

Original file line number	Diff line number	Diff line change
`@@ -110,7 +110,7 @@ function Browser(window, document, body, XHR, $log, $sniffer) {`
`110`	`110`	`} else {`
`111`	`111`	`completeOutstandingRequest(callback);`
`112`	`112`	`}`
`113`		`- delete window[callbackId];`
	`113`	`+ window[callbackId] = null;//IE7 IE8 don't like delete window[callbackId];`
`114`	`114`	`body[0].removeChild(script);`
`115`	`115`	`});`
`116`	`116`	`} else {`