Javascript Write File Without Overwrite

I am using XPCOM to read/write file(s) on my hard drive (since Java is no longer supported on FF16,17,18,+ I have to use this). I use it in my FireFox extension(s) (I use iMacros).

Solution 1:

Try passing 18 as the second parameter when you init the output stream (instead of 2).

fileStream.init(file, 18, 0x200, false);

That adds the PR_APPEND flag to the io mode parameter (it's 0x10; the 2 is for PR_WRONLY).