Module/function boilerplate using promises

promiseBoilerplate.js

/*
  Module boilerplate (jQuery)

    - Pass in a callback OR a promise
    - Always returns a promise
*/

function getStuff(arg, d) {
  var callback = d,                 // Save possible callback
      is_promise = d && d.resolve;  // Check whether d is a promise

  // If a promise was not passed in, create a new deferred
  if (!is_promise) d = $.Deferred();

  try {
    // Some (possibly) asynchronous operation
    asyncGet(arg, function (stuff) {
      // If using a classic callback, pass the result to it
      if (typeof callback === "function") callback(stuff);

      // Resolve the module deferred with the result
      d.resolve(stuff);
    });
  }
  catch (err) {
    // Something horribly wrong, reject the deferred with the error
    d.reject(err);
  }

  // Return the locked down version of the deferred (aka. promise)
  return d.promise();
}


/*
  Example use
*/

var stuff_promise = getStuff("my-stuff");

stuff_promise.then(
  function (stuff) { ... },
  function (err) { ... }
);