Alternative transport methods: Exception when calling the `failure` callback

Adding the following config causes exception Cannot use 'in' operator to search for 'status' in undefined

transport: (params, success, failure) => {
  // ...
  failure(err); // err object that has a `status` property.
}

I looked into the lib to find where the problem is. It’s exactly here

https://github.com/select2/select2/blob/develop/src/js/select2/data/ajax.js#L85

Where the $request will always be undefined.

Fix: Allow receiving an error param which we should check against.

function (err) { // <- Receive an error param here
  if ('status' in err && (err.status === 0 || err.status === '0')) {
    return;
  }
// ...

By the way, the docs says:

request.on('failure', failure);

that indicates that the failure call back accepts parameters.

If this issue and the fix are confirmed, I’m ready for the pull request!

---

Update: My current workaround:

transport: (params, success, failure) => {
  // ...
  setTimeout(() => failure(err)); // <-- #1
  // ...

   return { };  // <-- #2
}

[kevin-brown]

I believe the best solution would be to check if $request is not null first, before checking that it has the status property.

https://github.com/select2/select2/blob/d0ddab6cebc69e37fe51dfc287c3e3aa37b5cd1d/src/js/select2/data/ajax.js#L85

It’s an optional, undocumented feature of transports where you can have it detect an aborted request. We should be fully supporting the case where a transport doesn’t provide the status property.

[stale[bot]]

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