wrap a Promise with Ruby-esque block behavior; ES6/ES2015

wrap-promise.js

/*
Insert a Promise into a pre-defined Promise chain.

@param promiseBlock [Function] takes a Promise
  parameter & returns the continuation of that parameter.
@return [Promise] the fullfilled Promise chain
*/
function wrapPromise(promiseBlock) {
  if (typeof promiseBlock !== 'function') {
    throw new Error('promiseBlock must be a Function');
  }

  // Set-up source promise and local scope.
  var sourcePromise = Promise.resolve();

  return new Promise((resolve, reject) => {

    var resultPromise = promiseBlock(sourcePromise);
    if (!resultPromise || typeof resultPromise.then !== 'function') {
      throw new Error('promiseBlock must return a Promise');
    }

    return resultPromise
    .then((v) => {
      // clean-up
      resolve(v);
    })
    .catch((error) => {
      // clean-up
      reject(error);
    })
  })
  .catch((error) => { throw error });
}