I actually figured out an alternative for this particular case. I would create a client-side JavaScript object and store stuff there, then when they leave, it m

I actually figured out an alternative for this particular case. I would create a client-side JavaScript object and store stuff there, then when they leave, it makes one call to the server with the object passed as JSON. Problem then becomes cleaning the output. I was just thinking, if you can edit stuff in the browser console, can't you edit the contents of an array? I guess actually you wouldn't see that displayed in the code, it's a state maintained in browser memory I think. But I'm still considering this potential problem and making a known/limited pattern eg. numbers only separated by a known symbol like a dash to use for exploding/splitting.... anyway will try it out.