$('#form-account').validate({
      rules: {
          username: {
            required: true,
          },
          password: {
            required: true,
            minlength: 4
          },
          confirm_password: {
            required: true,
            equalTo: "#password"
          },
      },
      highlight: function(element) {
          $(element).closest('.form-group').addClass('has-error');
      },
      unhighlight: function(element) {
          $(element).closest('.form-group').removeClass('has-error');
          $(element).closest('.form-group').addClass('has-success');
      },
      errorElement: 'span',
      errorClass: 'help-block,

    });