javascript - Check if a preference exist from Firefox extension -

javascript - Check if a preference exist from Firefox extension -

how check if preference exist?

i need create new preference in firefox configuration, can't know whether exists already.

var firstrun = prefs.getboolpref('extensions.addon.firstrun');

error: ns_error_unexpected: component returned failure code: 0x8000ffff (ns_error_unexpected) [nsiprefbranch.getboolpref]

as stated @try-catch-finally, mdn has code snippets.

i utilize @try-catch-finally's user name :p, e.g.

var somepref = false; seek { firstrun = prefs.getboolpref('extensions.addon.somepref'); } grab (ex) { prefs.setboolpref('extensions.addon.somepref', somepref = true); }

well, even better if added default preferences (more) extension! "first run" preferences predestinated this.

in defaults/preferences/somefilename.js add together e.g.

pref("extensions.addon.firstrun", true);

make sure read through preferences article. in particular preference observers quite useful. ;)

javascript firefox firefox-addon