Know the Password behind the asterisks in your browser

Here is the Trick,

First open a browser and then goto http://mail.yahoo.com/ or http://www.gmail.com/ and then enter your user name and password but don't click on submit or don't click on login .
After entering the password, that password is hidden behind the asterisks.

Now clear the url on the browser and copy the below code and paste it there and hit enter.

javascript:(function(){var%20s,F,j,f,i;%20s%20=%20%22%22;%20F%20=%20document.forms;%20for(j=0;%20j