ASP Syntax
You can not
view ASP code in a browser, you will only see the output
from ASP which is plain HTML. This is because the
scripts are executed on the server before the result is
sent to the browser.
In our
school, every example displays the hidden ASP code. This
will make it easier for you to understand how it
works.
The Basic
Syntax Rule
An ASP file
normally contains HTML tags, just as a standard HTML
file. In addition, an ASP file can contain server
scripts, surrounded by the delimiters <% and %>.
Server scripts are executed on the server, and can
contain any expressions, statements, procedures, or
operators that are valid for the scripting language you
use.
The
Response Object
The Write
method of the ASP Response Object is used to send
content to the browser. For example, the following
statement sends the text "Hello World" to the
browser: Response.Write("Hello
World").
VBScript
In ASP it is
possible to use different scripting languages. The
default language in ASP is VBScript, as in this
example:
<html>
<body>
<%
response.write("Hello
World!")
%>
</body>
</html> |
The example
above uses the response.write function to write Hello
World! into the body of the HTML document.
JavaScript
To use
JavaScript as the default scripting language, insert a
language specification at the top of the
page:
<%@ language="javascript"
%>
<html>
<body>
<%
Response.Write("Hello
World!")
%>
</body>
</html> |
Note that -
unlike VBScript - JavaScript is case sensitive. You will
have to write your ASP code with uppercase letters and
lowercase letters when the language requires
it.
Other
Scripting Languages
ASP comes
with VBScript and JScript, Microsoft's implementation of
Javascript. If you want to script in another language,
like PERL, REXX, or Python, you have to install
scripting engines for them.
Because the
scripts are executed on the server, the browser that
requests the ASP file does not need to support
scripting.
ASP
Variables
A variable declared outside a
procedure, can be changed by any script in the ASP file.
A variable declared inside a procedure, is created and
destroyed every time the procedure is executed.
Lifetime
of Variables
A variable
declared outside a procedure can be accessed and changed
by any script in the ASP page in which it is
declared.
A variable
declared inside a procedure is created and destroyed
every time the procedure is executed. No scripts outside
that specific procedure can access or change that
variable.
To make a
variable accessible to several ASP pages, declare it
either as a session variable or as an application
variable.
Session
Variables
Session
variables store information about one single user, and
are available to all pages in one application. Common
information stored in session variables are username and
userid. To create a session variable, store it in a
Session Object.
Application Variables
Application
variables are also available to all pages in one
application. Application variables are used to hold
information about all users in a specific application.
To create an application variable, store it in an
Application Object.
ASP
Procedures
In ASP you can call a JavaScript
procedure from a VBScript and vice versa.
Procedures
ASP code can
contain procedures and functions:
<html>
<head>
<%
sub
vbproc(num1,num2)
response.write(num1*num2)
end
sub
%>
</head>
<body>
The result of the
calculation is: <%call
vbproc(3,4)%>
</body>
</html> |
Insert the
<%@ language="language" %> line above the
<html> tag if you want to write procedures or
functions in a scripting language other than the
default:
<%@ language="javascript"
%>
<html>
<head>
<%
function
jsproc(num1,num2)
{
Response.Write(num1*num2)
}
%>
</head>
<body>
The result of the
calculation is:
<%jsproc(3,4)%>
</body>
</html> |
Calling a
Procedure
When calling
a VBScript or a JavaScript procedure from an ASP page
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.
When calling
a JavaScript or a VBScript procedure from an ASP page
written in JavaScript, always use parentheses after the
procedure name.
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