Implement Promise::done() to rethrow Errors for unhandled rejections.

[johnyanarella]

One of the pitfalls of interacting with Promise-based APIs is the tendency for important errors to be silently swallowed unless an explicit rejection handler is specified.

For example:

var promise = doWork().then( function () {
  // logic in your callback throws an error and it is interpreted as a rejection.
  throw new Error('Boom!');
});

// The error is swallowed.

Q.js addresses this issue by introducing a done() method that terminates a chain of Promises, forcing subsequent rejections to be thrown as exceptions.

var promise = doWork().then( function () {
  // logic in your callback throws an error and it is interpreted as a rejection.
  throw new Error('Boom!');
}).done();

// The error is thrown on the next tick of the event loop.

The done() method ensures that unhandled rejections are rethrown.

[johnyanarella]

This feature and its associated unit tests have been implemented in the promises_aplus branch and will be part of the Deft JS 0.9 release.

[johnyanarella]

Deft.Promise::done() is now available as part of the new Promises/A+ compliant rewrite of Deft JS's Promises.

See also: #82