WScript / vbscript check if file in directory - csv

Question

IN THE BOTTOM CODE THAT WORKED
Working on a variation of Convert XLS to CSV on command line that I could use to copy xls as csv.
I just want to copy files that are not yet copied, so need to check if file already exists in my target directory.
Was thinking something like:
Set fso=CreateObject("Scripting.FileSystemObject")
Set sourcefldr=fso.getFolder(sourcepath)
Set targetfldr=fso.getFolder(targetpath)
for each sfile in sourcefldr.files
for each tfile in target
if not file in targetfldr.files then
'create excelfile and save as csv
however file in targetfldr.files not working
How can I avoid looping over all my target files every time?
tks in advance!
EDIT:
Incorporated #Pankaj Jaju and #Ansgar Wiechers answer and below is working!
csv_format = 6
sourcestring ="C:\sourcefolder"
deststring= "V:\destfolder"
Set fso=CreateObject("Scripting.FileSystemObject")
Set sourcefldr=fso.getFolder(sourcestring)
Set destfldr=fso.getFolder(deststring)
Dim oExcel
Set oExcel = CreateObject("Excel.Application")
Dim oBook
for each sfile in sourcefldr.files
destname = left(sfile.name,len(sfile.name)-3) & "csv"
fulldest = fso.buildpath(destfldr, destname)
if not fso.FileExists(fulldest) then
Set oBook = oExcel.Workbooks.Open(sfile)
oBook.SaveAs fulldest, csv_format
oBook.Close False
WScript.Echo "Copied " & fulldest
end if
next
oExcel.Quit

Answer 1

Try this !
set fso=createobject("scripting.filesystemobject")
set sourcefldr=fso.getfolder(sourcepath).files
for each sfile in sourcefldr
if not fso.fileexists(fso.buildpath(targetpath, sfile.name)) then
fso.getfile(sfile).copy(fso.buildpath(targetpath, sfile.name))
end if
next

Answer 2

Best bet would be add all of your target folder files into a dictionary. This way you can just use "Exists" to search for it in the dictionary.
Set fso=CreateObject("Scripting.FileSystemObject")
Set filesDic = CreateObject("Scripting.Dictionary")
Set targetfldr=fso.getFolder(targetpath)
'add destination files into dictionary
For Each file in targetfldr.files
filesDic.Add file.name, file.name
Next
This way all you need to do is check the new filename against the dictionary
filesDic.Exists(file.name)
This will just return a true / false
Here is a bit more information about the dictionary http://www.devguru.com/technologies/vbscript/13992