🧰 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

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📘 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

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📚 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")
%>

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🗝️ 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.

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📤 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"

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💡 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.

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❗ 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.

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📂 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

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📂 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.

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🧾 ASP – Dictionary Object

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

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

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🎞️ ASP – Ad Rotator

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

✅ ads.txt should list banners with descriptions and links.

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🧠 ASP – BrowserCap

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

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

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🔗 ASP – Content Linking

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

✅ Use QueryString values to build navigation and filters.

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🔄 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.

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📌 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

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❓ Frequently Asked Questions

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

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

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

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

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