ASP Lesson 2:- ASP Procedures and Form Inputs
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ASP Procedures
The ASP source code can contain procedures and functions:
<html>
<head>
<%
sub vbproc(num1,num2)
response.write(num1*num2)
end sub
%>
</head><body>
<p>Result: <%call vbproc(3,4)%></p>
</body></html>
Insert the <%@ language="language" %> line above the <html>
tag to write procedures or functions in another scripting language than default:
<%@ language="javascript" %>
<html>
<head>
<%
function jsproc(num1,num2)
{
Response.Write(num1*num2)
}
%>
</head><body>
<p>Result: <%jsproc(3,4)%></p>
</body></html>
Differences Between VBScript and JavaScript in Asp
In ASP when calling a VBScript or a JavaScript procedure from an ASP file written
in VBScript, you can use the "call" keyword followed by the procedure
name. If a procedure requires parameters, the parameter list must be enclosed
in parentheses when using the "call" keyword. If you omit the "call"
keyword, the parameter list must not be enclosed in parentheses. If the procedure
has no parameters, the parentheses are optional.
Thus in ASP, when calling a JavaScript or a VBScript procedure from an ASP
file written in JavaScript, always use parentheses after the procedure name.
ASP User Input
The Request object may be used to retrieve user information from forms:
<form method="get" action="simpleform.asp">
First Name: <input type="text" name="fname">
<br />
Last Name: <input type="text" name="lname">
<br /><br />
<input type="submit" value="Submit">
</form>
User input can be retrieved in two ways: With Request.QueryString or Request.Form.
ASP Request.QueryString
The ASP Request.QueryString command is used to collect values in a
form with method="get". Information sent from a form with the GET
method is visible to everyone (it will be displayed in the browser's address
bar) and has limits on the amount of information to send.
If a user typed "Bill" and "Gates" in the form example
above, the URL sent to the server would look like this:
http://compbuy.co.uk/webdesign/simpleform.asp?fname=Bill&lname=Gates
Assume that the ASP file "simpleform.asp" contains the following
script:
<body>
Welcome
<%
response.write(request.querystring("fname"))
response.write(" " & request.querystring("lname"))
%>
</body>
ASP Request.Form
The ASP Request.Form command is used to collect values in a form with method="post".
Information sent from a form with the POST method is invisible to others and
has no limits on the amount of information to send.
If a user typed "Bill" and "Gates" in the form example
above, the URL sent to the server would look like this:
http://compbuy.co.uk/webdesign/simpleform.asp
Assume that the ASP file "simpleform.asp" contains the following
script:
<body>
Welcome
<%
response.write(request.form("fname"))
response.write(" " & request.form("lname"))
%>
</body>
ASP Form Validation
User input should be validated on the browser whenever possible (by client scripts).
Browser validation is faster and you reduce the server load.
You should consider using server validation if the user input will be inserted
into a database. A good way to validate a form on the server is to post the
form to itself, instead of jumping to a different page. The user will then get
the error messages on the same page as the form. This makes it easier to discover
the error. | 
