Create folder when upload file

Hi, I need your help.
Using a script for upload files I would like to manage this:
1) select file
2) check if exist a folder named "ID" of the page (this is a variable)
if the folder exists, upload the file selected in this folder
if doesn't exists, create the folder (ID) and upload the file
 
Can you help me to manage this upload problem?

Thanks

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