Page 72 - DCAP312_WEB_TECHNOLOGIES_II

Web Technologies-II

Notes Function CheckForm(form)
{
for(var intCtr = 0; intCtr <= (form.elements.length - 5);
++intCtr)
{
var temp = form.elements[intCtr];
if(temp.type == “text” && temp.value == “”)
{
alert( “Please Enter All Information!”);
temp.focus();
return false;
}
}
return true;
}
//-->
</script>
This sample piece of JavaScript does some validation, but it does not check for all the information
that we might need on the form we are building. This piece of code determines only whether
the user entered anything at all in all five fields within the form. It does not determine whether
the user entered an actual e-mail address within the e-mail address text box, whether the user
entered a number between two given numbers, or whether the password and the confirm
password text boxes match. After awhile, we can see that we need many JavaScript functions
to obtain the level of form validation required.
4.2.2 .NET to the Rescue

Developers who used classic Active Server Pages 3.5 to develop Web pages might keep in mind
that they used to use up a considerable quantity of their time initial validation workings in their
page. It was time consuming if we did it right. It was most efficient to do the validation of the
form on the client-side to limit the number of requests and responses required to work through
an application. However, we were never quite sure if the requesting browser would understand
the scripting code that we used for the validation. So, it was usually better, especially for critical
Web applications, to bring the validation to the server.

ASP.NET has distorted this by giving us the potential to use the corroboration server controls
that are provided with the other new controls at our disposal. What makes these validation
server controls effective is that when an ASP.NET page containing these controls is requested,
it is the ASP.NET engine that decides whether to perform the validation on the client or on the
server depending on the browser that is making the request. Therefore, our page’s functionality
changes depending on the requesting browser—thus enabling us to make our Web pages the
best they can possibly be rather than dummying-down our Web applications for the lowest
common denominator. Validation server controls are the only type of ASP.NET server controls
that also generate client-side script. All the other controls work with the idea of making post
backs to the server (a request to the server to get a response).
Six different validation server controls are available for ASP.NET:
1. RequiredFieldValidator

2. CompareValidator

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