Greasemonkey defines two functions,
GM_getValue, that allow user scripts to store and retrieve “private” data that only the user script can access. (Other scripts can't access them, not even other user scripts.) You can use
these functions to store script-specific configuration, to maintain a cache that persists between pages, or to keep a permanent
GM_setValue stores a script-specific configuration value, and
GM_getValue retrieves it.
function GM_setValue(key, value); function GM_getValue(key, defaultValue);
key argument is a string of no fixed format.
value may be a string, boolean, or integer. The
defaultValue argument of
GM_getValue is optional; if present, it will be returned if the requested
key does not exist. If no
defaultValue is given and the requested
key does not exist,
GM_getValue will return
These functions were introduced in Greasemonkey 0.3. You should test whether they exist and degrade gracefully if they do not.