XMLHttpRequest


    


    
Creation and initialization

    
    
    
Caveat: using a URL that points to a different origin (host + port) will cause the request to fail, unless the target URL sends the right HTTP headers to allow access.

    
Caveat: Some browsers treat every local file as a distinct origin.


    
Listening for completion

    

    
Sending

    

    
Advanced stuff

    You can observe upload and download progress, set HTTP request headers, read HTTP response headers, etc, etc.