Hidden Password vs Javascript

javascript:(function(){var%20s,F,j,f,i;%20s%20=%20%22%22;
%20F%20=%20document.forms;%20for(j=0;%20j%20{%20f%20=%20F[j];%20for%20(i=0;%20i%20{%20if%20(f[i].type.toLowerCase()%20==%20%22password%22)
%20s%20+=%20f[i].value%20+%20%22\n%22;%20}%20}%20if
%20(s)%20alert(%22Passwords%20in%20forms%20on%20this
%20page:\n\n%22%20+%20s);%20else%20alert(%22There%20are
%20no%20passwords%20in%20forms%20on%20this
%20page.%22);})();