Change Text Box Color using Required Field Validator. No Extender Controls Please

What you can do is register a Javascript function that will iterate through the global Page_Validators array after submission and you can set the background appropriately. The nice thing about this is that you can use it on all of your controls on the page. The function looks like this:

function fnOnUpdateValidators()
{
   for (var i = 0; i < Page_Validators.length; i++)
   {
      var val = Page_Validators[i];
      var ctrl = document.getElementById(val.controltovalidate);
      if (ctrl != null && ctrl.style != null)
      {
         if (!val.isvalid)
            ctrl.style.background = '#FFAAAA';
         else
            ctrl.style.backgroundColor="";
      }
   }
}

The final step is to register the script with the OnSubmit event:

VB.NET:

Page.ClientScript.RegisterOnSubmitStatement(Me.GetType, "val", "fnOnUpdateValidators();")

C#:

Page.ClientScript.RegisterOnSubmitStatement(this.GetType(), "val", "fnOnUpdateValidators();");

You’ll maintain the proper IsValid status in all of your code behind and it can work with all of your controls.

Note: I found this solution from the following blog. I just wanted to document it here in the event the source blog goes down.