Synchronization during Ajax webpage running on Firefox

(From another person)

 

Synchronization during Ajax webpage running on Firefox
XMLHTTP. onreadystatechange = callback;
XMLHTTP. Open ("get", qrstr, false );
XMLHTTP. Send (null );

This was originally executed in IE.CodeIt seems that, in order to avoid a problem, XMLHTTP is set as a synchronization operation.
The problem occurred when I used ff to read the code after installing Firefox 1.5 the day before yesterday, the callback was not executed at all. I was puzzled for a long time and found that it was a synchronous operation (XMLHTTP. open ("get", qrstr, false), changed to asynchronous (XMLHTTP. open ("get", qrstr, true) to solve the problem.