$('#pass').keyup(function(e) {
 var strongRegex = new RegExp("^(?=.{8,})(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*\\W).*$", "g");
 var mediumRegex = new RegExp("^(?=.{7,})(((?=.*[A-Z])(?=.*[a-z]))|((?=.*[A-Z])(?=.*[0-9]))|((?=.*[a-z])(?=.*[0-9]))).*$", "g");
 var enoughRegex = new RegExp("(?=.{6,}).*", "g");
 if (false == enoughRegex.test($(this).val())) {
 $('#passstrength').html('More Characters');
 } else if (strongRegex.test($(this).val())) {
 $('#passstrength').className = 'ok';
 $('#passstrength').html('Strong!');
 } else if (mediumRegex.test($(this).val())) {
 $('#passstrength').className = 'alert';
 $('#passstrength').html('Medium!');
 } else {
 $('#passstrength').className = 'error';
 $('#passstrength').html('Weak!');
 }
 return true;
});

<input type="password" name="pass" id="pass" />
<span id="passstrength"></span>