Firefox has restricted use of synchronous XMLHttpRequest in some cases. I don't know whether there is a good page summarizing the changes, so I'm not sure whether your example is affected by them. Could you try setting async to true? I realize this requires other code changes, so perhaps wait for other comments.

I've tried synchronous/asynchronous. Nothing seems to work. I must be missing something obvious. Does anyone have an example of using JS and PHP with the current version of Firefox? Thanks

Is there anything relevant in the Error Console (Ctrl+Shift+j)?

Is the requesting page located on the identical hostname and port number?

The error console message is

Timestamp: 2012-06-26 11:40:55 Error: uncaught exception: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE)" nsresult: "0x80004005 (NS_ERROR_FAILURE)" location: "JS frame :: http://localhost/Library/dbfuncs.js :: sendQuery :: line 69" data: no]

This is all running on my PC using Wampserver

I think Firefox might consider this a cross-site request if you are running your script on port 80 and sending a request to port 8080. Is that necessary? There is a mechanism for permitting such requests, as described in this article: HTTP access control (CORS) - MDN.

I'm not trying to do a cross-site request. I've tried using

'http://Localhost:8080/Library/dbRequest.php/' and

'http://Localhost:80/Library/dbRequest.php/'

but I still get the same error.

If I leave out the 'http://Localhost:8080/ part I do get a cross-site error 8012.

It's very frustrating because I used to be able to do everything I want but now I can't.

Thanks for help.