How can a Firefox extension get its own version number programmatically?

Question

How do I programatically get my own Firefox extension's version number with Javascript? My extension has an install.rdf file containing the version number similar to below. I want to extract the contents of the `` tag. ``` ... 1.0 ... ```

Accepted Answer

I've not got the full answer, but I found the Extended extension and had a look at the source code as it seemed like a good starting point, and from Googling some of the methods in that I found this snippet on MDC. The key bit of code would seem to be this:

```
var gExtensionManager = Components.classes["@mozilla.org/extensions/manager;1"]
                        .getService(Components.interfaces.nsIExtensionManager);
var current = gExtensionManager.getItemForID("extension@guid.net").version;
```

You would have to replace `extension@guid.net` with the appropriate ID for your extension.

Firefox 4 requires different code, see the other answer.

How can a Firefox extension get its own version number programmatically?

Solution

Problem