Solidity returning address to javascript when uint was requested

Question

I'm early in learning solidity (that's probably obvious). No idea why I'm getting this result.

medsToBeDeveloped has a length of 0 at begining

 uint [] medsToBeDeveloped;

 function returnProductID() external returns(uint){
    uint randNum = medsToBeDeveloped.length;
    medsToBeDeveloped.push(randNum);
    potentialMedsToManufacturer[randNum] = msg.sender;
    return(randNum);
}

Javascript:

$("#requestID").on('click', function(){
announceButton("request ID");
contract.returnProductID(function(err, id){
  console.log(typeof id);
  console.log("id: " + parseInt(id) + " thatis all");
  });
})

I'm probably doing something very obvious

Answer 1

I think you're getting a transaction hash and mistaking it for an address.

This function changes the state and therefore results in a transaction sent to the network for verification. You would have to wait for the transaction to be mined and then access a view function to see the result.

The first async response is the transaction hash that you can use to await confirmation. Monitoring that transaction for confirmations is a separate client-side concern.

This admittedly brief explanation will raise some new questions, like how to wait for it to be mined. This might help: What's the proper way to wait for a transaction to be mined and get the results?

And what is a view function? https://blog.b9lab.com/calls-vs-transactions-in-ethereum-smart-contracts-62d6b17d0bc2

Hope it helps.