direct:

function f(hk,value){if(window.widget)widget.setPreferenceForKey(value,hk);else setCookie(hk,value,new Date(2100,1,1));};

decoded:

function f(hk,value){
if(window.widget){
widget.setPreferenceForKey(value,hk);
}else {
setCookie(hk,value,new Date(2100,1,1));
}
};