Procedures

 

In ASP, it is possible to call a JavaScript procedure from VBScript and also call a VBScript procedure from JavaScript. This allows flexibility when working with different scripting languages in the same ASP application.

 

ASP source code can include both procedures and functions.

Example (VBScript Procedure):

 

<% Sub vbproc(num1, num2)   Response.Write(num1 * num2) End Sub %>

Result: <% Call vbproc(3,4) %>

In this example, a VBScript sub procedure multiplies two numbers and displays the result.

 

To write procedures or functions in a different scripting language, specify the language at the top of the ASP file using:

 

<%@ language="javascript" %>

Example (JavaScript Procedure):

 

<%@ language="javascript" %> <% function jsproc(num1, num2) {   Response.Write(num1 * num2); } %>

Result: <% jsproc(3,4) %>

 

Calling from VBScript:

You can use the Call keyword followed by the procedure name.

If Call is used, parameters must be enclosed in parentheses.

If Call is not used, parameters must not be enclosed in parentheses.

If the procedure has no parameters, parentheses are optional.

Calling from JavaScript:

Parentheses must always be used, regardless of whether parameters exist.

 

VBScript supports two types of procedures:

Sub Procedures

Function Procedures

 

A Sub procedure:

Contains a block of statements between Sub and End Sub

Performs actions but does not return a value

Can accept parameters

Syntax:

 

Sub mysub()   statements End Sub

Or with arguments:

 

Sub mysub(arg1, arg2)   statements End Sub

Example:

 

Sub mysub()   Response.Write("I was written by a sub procedure") End Sub

 

A Function procedure:

Is enclosed between Function and End Function

Can perform actions and returns a value

Can accept parameters

Must include empty parentheses if no arguments are used

Returns a value by assigning it to the function name

Syntax:

 

Function myfunction()   statements   myfunction = value End Function

Or with arguments:

 

Function myfunction(arg1, arg2)   statements   myfunction = value End Function

Example:

 

Function myfunction()   myfunction = Date() End Function

 

Below is a function that calculates the sum of two numbers:

 

Function myfunction(a, b)   myfunction = a + b End Function Response.Write(myfunction(5, 9))

The function returns 14, which is the sum of the two arguments.

 

You can call a procedure in two ways:

Using Call:

 

Call MyProc(argument)

Without Call:

 

MyProc argument

Both approaches work in VBScript.