convert-to-async

jquery-callbacks.js

// If the function does not take an 'errback' callback, we can still wrap our 
// functions. Let's use a fictional method:
fictionalMethod(data, successCallback, failureCallback) {
  fictionalAsyncOperation(data, result => {
    if ( !result ) {
      return failureCallback(new Error('Result not found'))
    } else {
      return successCallback(result);
    }
  })
}

// We would use this method, traditionally, like so:
fictionalMethod({ foo: 'bar' }, (result) => {
  res.json(result);
}, (err) => {
  throw err;
});

// Here's what our promise wrapper looks like.
// The outer wrapping and rest/spreading is unchanged.
// We simply need to modify the inner callback to resolve/reject 
// based on the signature of the wrapped function.
function wrapWithPromise(wrappedFunction, ...args) {
  return new Promise((resolve, reject) => {
    wrappedFunction(...args, (result) => {
      return resolve(result);
    }, (err) => {
      return reject(err);
    });
  });
}