GM.getValue
From GreaseSpot Wiki
Syntax
GM_getValue( name, default )
Description
Retrieve a value set with GM_setValue. Values are saved in the Firefox preferences back end and can be changed by typing about:config
in the address bar and searching for the preference name "greasemonkey.scriptval.script-namespace/script-name.
If the value is not found, default is returned instead.
If default is not supplied, undefined
is returned.
Examples
alert(GM_getValue("foo"));