Identifying the operating system with XPCOM

The following shows how to get a string identifying the current operating system from an instance of nsIXULRuntime:

var getOS = function() {
var env = Components.classes[";1"].getService(Components.interfaces.nsIXULRuntime);
return env.OS;

The nsIXULRuntime.OS string is one of the OS_TARGET values.

Ideally, I’d prefer XUL and XPCOM code to remain platform-agnostic, but I’ve used OS detection as a cheap way (versus jumping through 3 objects) to determine what path separator to use when referencing files and directories (backslash for “WINNT”, forward-slash for everything else). XPCOM is sensitive to the path separator; on Windows, it will not reference a file or directory if you use the forward slash. This is actually bizarre because Win32 API functions will accept paths with the forward slash as a separator. Even more bizarre is that we have a layer of abstraction that actually makes it harder to write platform-independent code.

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