Question

I need your help.

I’d like to be able to have a file naming system that would detect if the filename exists and if it does automatically add a number at the end of it. Starting at 2

ie.

var myString = "2011-1234567";

myString = myString + "-2";

if (2011-1234567-2 already exists) then output new file number as: 2011-1234567-3 

so id like to ideally be able to create a function that would automatically add a number at the end of it if the filename already exists

Answer 1

var exists = 0
function file_exists(name) {
   // replace with something suitable for your environment
   exists = 1 - exists 
   return exists
}

function new_name(suggested) {
   // just return back new name if it available
   if (!file_exists(suggested)) { return suggested }
   // try to split name to "base" and "index" parts
   var have_index = suggested.match(/^(.+)\-(\d+)$/)
   var unused_index
   if (have_index && have_index[2]) {
      base = have_index[1]
      unused_index = ++have_index[2]
   } else {
      // use entire name and start from index 2 if not found
      base = suggested
      unused_index = 2
   }
   // loop until you find next free index
   while (file_exists(base  + "-" + unused_index)) { unused_index++ }
   // ... and return result
   return base  + "-" + unused_index
}

Running new_name("tommy"), gives “tommy-2”. new_name("tommy-2") – “tommy-3”, etc. Of course you need to define your own vision of “exists” in file_exists function.