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Common ASP References – VBScript, Server Objects, File APIs & Helpers

Introduction – Build Efficient Classic ASP Apps with Reusable Helpers

Classic ASP comes equipped with a powerful set of built-in functions, objects, and APIs that make dynamic web development possible. From handling file systems and errors to rotating ads and detecting browsers, these shared references form the backbone of many classic web applications.

In this guide, you’ll learn:

Frequently used VBScript functions and keywords in ASP
How to use Request, Response, and Server objects
How to manage files using the FileSystemObject API
How to handle errors and work with dictionaries
How to rotate content and ads dynamically

Topics Covered

Topic	Description
ASP – VB Functions	Commonly used VBScript functions for string, math, and date handling
ASP – VB Keywords	Reserved words and syntax used in Classic ASP scripting
ASP – Response / Request	Read inputs and send output to browser
ASP – Server Object	Access file system, components, pathing, and encoding
ASP – Error Handling	Use `On Error Resume Next` and `Err` object
ASP – File System API (Files/Folders)	Read, write, delete files or folders on the server
ASP – File System API (Drive/TextStream)	Inspect drives, read/write text files
ASP – Dictionary Object	Store key-value pairs in memory like a hashtable
ASP – Ad Rotator	Rotate banner ads from XML or text file
ASP – BrowserCap	Detect browser type and capabilities
ASP – Content Linking	Create navigable, linked content dynamically
ASP – Content Rotator	Show different text/images on each page load

ASP – VB Functions

Commonly used VBScript functions in Classic ASP:

Function	Use Case
`Len()`	Get string length
`Trim()`	Remove extra spaces
`Now()`	Current date and time
`DateAdd()`	Add intervals to dates
`UCase()`	Convert string to uppercase
`IsEmpty()`	Check if variable is uninitialized

Example:

<%
Response.Write UCase("hello")
%>

ASP – VB Keywords

Key reserved words in VBScript for control flow and logic:

If, Then, Else, End If
Select Case, Case
For, Next, Do, While, Loop
Function, Sub, Call
Dim, Set, Const

Must avoid using them as variable names.

ASP – Request / Response Objects

Read Input:

name = Request.Form("name")

Write Output:

Response.Write "Welcome " & name

Response can also handle headers:

Response.AddHeader "Content-Type", "text/plain"

ASP – Server Object

Access server resources:

Set fs = Server.CreateObject("Scripting.FileSystemObject")
path = Server.MapPath("data.txt")
encoded = Server.HTMLEncode("<b>bold</b>")

CreateObject, MapPath, URLEncode, HTMLEncode are commonly used.

ASP – Error Handling

On Error Resume Next
Set conn = Nothing
If Err.Number <> 0 Then
  Response.Write "Error: " & Err.Description
  Err.Clear
End If

Always clear the error after handling it.

ASP – File System API (FileSystemObject)

Set fs = Server.CreateObject("Scripting.FileSystemObject")
Set file = fs.OpenTextFile(Server.MapPath("data.txt"), 1)
text = file.ReadAll
file.Close

File Modes:

1 = Read
2 = Write
8 = Append

ASP – File System API (Drive/TextStream)

Set d = fs.GetDrive("C:")
Response.Write "Free space: " & d.FreeSpace

Set txt = fs.CreateTextFile(Server.MapPath("log.txt"), True)
txt.WriteLine "Log entry"
txt.Close

Can inspect drives and log diagnostics.

ASP – Dictionary Object

Set dict = Server.CreateObject("Scripting.Dictionary")
dict.Add "name", "Alice"
Response.Write dict.Item("name")

Use .Exists, .Remove, .RemoveAll for management.

ASP – Ad Rotator

<!--#include file="adrotator.inc"-->
<%
Randomize
DisplayAd "ads.txt"
%>

ads.txt should list banners with descriptions and links.

ASP – BrowserCap

browser = Request.ServerVariables("HTTP_USER_AGENT")
Response.Write browser

Or use BrowserCap.ini for advanced browser detection (requires config).

ASP – Content Linking

link = "page.asp?id=" & articleID
Response.Write "<a href='" & link & "'>Read More</a>"

Use QueryString values to build navigation and filters.

ASP – Content Rotator

Simple content switcher:

contentList = Array("Welcome!", "Hello!", "Thanks for visiting.")
Randomize
i = Int((UBound(contentList) + 1) * Rnd)
Response.Write contentList(i)

Great for rotating tips, quotes, or headlines.

Summary – Recap & Next Steps

Classic ASP offers a rich toolkit of built-in functions and objects that streamline file handling, user input, error management, and dynamic output. These reusable helpers are key to building and maintaining robust legacy web apps.

Key Takeaways:

VBScript functions simplify strings, dates, and math operations
Request, Response, and Server are the core I/O interfaces
FileSystemObject allows server-side file and folder manipulation
Dictionary, Ad Rotator, and BrowserCap add flexibility to UIs

Real-World Applications:

File upload logging and email forms
Banner ad rotation for monetization
Form field validation with VBScript
Session-aware UI logic and page includes

Frequently Asked Questions

What is the FileSystemObject in ASP?
It allows you to read, write, delete, and inspect files and directories on the server.

How do I handle errors gracefully in Classic ASP?
Use On Error Resume Next, then check Err.Number and Err.Description.

Can I use dictionaries in Classic ASP like hashtables?
Yes, using Scripting.Dictionary.

What’s the purpose of Server.MapPath?
Converts virtual paths to physical server paths (e.g., "/data.txt" → "C:\inetpub\...").

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