I'm sure that this script will help you in some of your projects that needs a username and password.
Sometimes when we want access to a secure page that asks for a username and password and we submit the information but we didn't know that the password was submitted in upper case, we get an error.
 
Solution: 

jQuery('#username').keypress(function(e) {
var s = String.fromCharCode( e.which );
if ( s.toUpperCase() === s && s.toLowerCase() !== s && !e.shiftKey ) {
jQuery('#capslockdiv').show();
}
else {
jQuery('#capslockdiv').hide();
}
});
jQuery('#password').keypress(function(e) {
var s = String.fromCharCode( e.which );
if ( s.toUpperCase() === s && s.toLowerCase() !== s && !e.shiftKey ) {
jQuery('#capslockdiv').show();
}
else {
jQuery('#capslockdiv').hide();
}
});

Sample HTML code