Selecting a Random File from a Directory and Outputting its Contents Demo

This demo illustrates how to have a random text file read from a directory and have its contents displayed. Below you will see the output of a random text file from the directory of (very) old WebWeekly issues.

WebDaily: Your daily source for Web Technology Tips and Tricks! -Forward this email and subscription information to a fellow developer!********************************************************************** More VBScript-to-JavaScript Functions*********************************************************************** This article provides code for a number of VBScript-to-JavaScriptconvertions.Here are some more useful VBScript-to-JavaScript functions:Len(String) : Returns the number of characters in a string=========================================================== function Len(str) /*** IN: str - the string whose length we are interested in RETVAL: The number of characters in the string ***/ { return String(str).length; }Left(string, length): Returns a specified number of characters from the left side of a string======================================================================== function Left(str, n) /*** IN: str - the string we are LEFTing n - the number of characters we want to return RETVAL: n characters from the left side of the string ***/ { if (n <= 0) // Invalid bound, return blank string return ""; else if (n > String(str).length) // Invalid bound, return return str; // entire string else // Valid bound, return appropriate substring return String(str).substring(0,n); }Right(string, length): Returns a specified number of characters from the right side of a string======================================================================== function Right(str, n) /*** IN: str - the string we are RIGHTing n - the number of characters we want to return RETVAL: n characters from the right side of the string ***/ { if (n <= 0) // Invalid bound, return blank string return ""; else if (n > String(str).length) // Invalid bound, return return str; // entire string else { // Valid bound, return appropriate substring var iLen = String(str).length; return String(str).substring(iLen, iLen - n); } }Mid(string, start, length): Returns a specified number of characters from a string============================================================================ function Mid(str, start, len) /*** IN: str - the string we are LEFTing start - our string's starting position (0 based!!) len - how many characters from start we want to get RETVAL: The substring from start to start+len ***/ { // Make sure start and len are within proper bounds if (start < 0 || len < 0) return ""; var iEnd, iLen = String(str).length; if (start + len > iLen) iEnd = iLen; else iEnd = start + len; return String(str).substring(start,iEnd); }// Keep in mind that strings in JavaScript are zero-based, so if you ask// for Mid("Hello",1,1), you will get "e", not "H". To get "H", you would// simply type in Mid("Hello",0,1)// You can alter the above function so that the string is one-based. Just// check to make sure start is not <= 0, alter the iEnd = start + len to// iEnd = (start - 1) + len, and in your final return statement, just// return ...substring(start-1,iEnd)I am starting a repository of VBScript-to-JavaScript functions. If you'dlike to browse the current function list, look no further thanhttp://www.4GuysFromRolla.com/webtech/vb2java.shtmlHappy Programming!****************************************************************************************************************************************** To subscribe to WebDaily, point your browser to: http://www.4GuysFromRolla.com/webtech/webdaily To unsubscribe from WebDaily, reply to this email with the following subject: UNSUBSCRIBE WEBDAILY******************************************************************************************************************************************Thank you for subscribing to WebDaily!If you know someone who could benefit from a wealth of web developmenttechnology, invite them to visit http://www.4GuysFromRolla.com/new

Source Code
<%
Option Explicit

Function ReadDir(FolderName)
	On Error Resume Next
	Dim objFSO
	Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
		
	'Make sure the specified folder exists
	If Not objFSO.FolderExists(FolderName) Then
		ReadDir = "Folder does not exist. <br><b>This can be changed to " & _
				"a default message or nothing.</b>"
		Exit Function
	End If

	Dim objFolder
	Set objFolder = objFSO.GetFolder(FolderName)

	Dim I : I = -1
	ReDim arrFile(20)
	Dim objFile
	For Each objFile In objFolder.Files
		If Right(objFile, 4) = ".txt" Then
  			I = I + 1
			
			if I > UBound(arrFile) then ReDim Preserve arrFile(I + 20)
						
			arrFile(I) = objFile.Path
		End If
	Next
	
	'Make sure arrFile is the right size
	Redim Preserve arrFile(I)

    If I = -1 Then
		ReadDir = "No text files in this directory. <br><b>This can be " & _
		          "changed to a default message or nothing.</b>"
		Exit Function
	End If

	Randomize
	Dim RanFile : RanFile = Int((UBound(arrFile) - 1 + 1) * Rnd + 1)
	Dim strOutput : strOutput = ""
	Dim strFileName : strFileName = arrFile(RanFile)
	If objFSO.FileExists(strFileName) Then
		Dim objTextStream
		Set objTextStream = objFSO.OpenTextFile(strFileName, 1)
			Do While Not objTextStream.AtEndOfStream
				strOutput = strOutput & objTextStream.ReadLine
			Loop
		objTextStream.Close
	Else
		ReadDir = "File does not exist. <br><b>This can be changed to a " & _
		          "default message or nothing.</b>"
		Exit Function
	End If
 
	
    ReadDir = strOutput
 
 Set objTextStream = Nothing
 Set objFolder = Nothing
 Set objFile = Nothing
 Set objFSO = Nothing
End Function
%>

<h1>Selecting a Random File from a Directory and Outputting its Contents Demo</h1>
...

<%
  Response.Write(ReadDir(Server.MapPath("/webtech/WebDaily")))
%>

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