看看这些:
jQuery验证插件 [ ASP.NET MVC3中的自定义客户端验证 [ ^ ]
MSDN:ASP.NET MVC 3自定义验证 [

Have a look at these:
jQuery validation plugin[^]
Custom Client Side Validation in ASP.NET MVC3[^]
MSDN: ASP.NET MVC 3 Custom Validation[^]

用户名文本框必填字段的说明.

say for required field for Username textbox.

函数validate()
{
var txtValue =

function validate()
{
var txtValue =

(``#txtUsername'').val();

如果(txtValue ==''''|| txtValue == null || txtValue ==未定义)
{
警报(``需要用户名.'');

(''#txtUsername'').val();

if (txtValue == '''' || txtValue == null || txtValue == undefined)
{
alert (''Username is required.'');