Question

I am looking into this New EmailAddressAttribute part of their source code here. Code look like as follows. I am just wondering if there should be any client side script provided with it as this class implements IClientValidatable interface as well.

public sealed class EmailAddressAttribute : DataTypeAttribute, IClientValidatable {
        private static Regex _regex = new Regex(@"^([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$", RegexOptions.Compiled | RegexOptions.IgnoreCase);

        public EmailAddressAttribute()
            : base(DataType.EmailAddress) {
            ErrorMessage = MvcResources.EmailAddressAttribute_Invalid;
        }

        public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) {
            yield return new ModelClientValidationRule {
                ValidationType = "email",
                ErrorMessage = FormatErrorMessage(metadata.GetDisplayName())
            };
        }

        public override bool IsValid(object value) {
            if (value == null) {
                return true;
            }

            string valueAsString = value as string;
            return valueAsString != null && _regex.Match(valueAsString).Length > 0;
        }
    }
}

Answer 1

Client validation is done unobtrusively based on html5 attributes that are attached to the element being validated (i.e. <input type="text" data-val-required="The field is required." />).

The java-script is in a static library and is based on jquery validate.