Do not use Promise.prototype.then()

Do not use Promise.prototype.then()

renderJS uses internally Nexedi's fork of RSVP, which allows to cancel promise.

Using the .then method creates a new Promise object, preventing to cancel the predecessor promises.

Use RSVP.Queue() promise and chain asynchronous call with the .push method.

Good example:

return new RSVP.Queue(RSVP.delay(10))
  .push(function () {
    return "OK";
  });

Bad example:

return RSVP.delay(10)
  .then(function () {
    return "OK";
  });