<script>
 
//下面的正则表达式建议各位收藏哦，项目上有可能会用得着
$(function(){  
  $('#pass').blur(function(e) {
    // alert('---------');
     //密码为八位及以上并且字母数字特殊字符三项都包括
     var strongRegex = new RegExp("^(?=.{8,})(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*\\W).*$", "g");
   
   //密码为七位及以上并且字母、数字、特殊字符三项中有两项，强度是中等 
     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;
  });
}); 
</script> 
         
<input type="password" name="pass" id="pass" /> 
<span id="passstrength"></span>