XMLHttpRequests (XHR) are used for lots of things these days. When running a background XHR, however, you might experience some common issues like authentication or bad SSL certificate dialogs popping up. Another problem was starting an XHR, then closing the window – the XHR is closed. To help get around these inconveniences, Manish Singh (of Flock) adding support for a background mode (bug 383430). The details:
- Do not attach to a window’s load group, so requests aren’t cancelled if the window closes (often the window isn’t really associated with the request anyway)
- Do not get an nsIAuthPrompt by default, since we don’t want authentication dialogs to pop up randomly.
- Provide an nsIBadCertListener implementation, again to prevent bad certificate dialogs to pop up randomly.
var req = new XMLHttpRequest(); req.mozBackgroundRequest = true; req.open("GET", someURI); req.send(null);
The magic is handled by
mozBackgroundRequest and it’s only available to chrome, not for web content.