Gets a single promise for multiple function returning their own promises. Allows for sequential promise execution and asynchronous promise execution.

getMultiPromise.js

/**
 * Gets a single promise for multiple function returning their own promises.
 * Allows for sequential promise execution and asynchronous promise execution.
 * @param {Array<(function():Promise|Array<function():Promise>)>} promiseMakers
 *   An array which can contain functions and arrays of functions.  Each
 *   top-level function when called must return a promise that will be waited
 *   for sequentially.  In the case of an item in the top-level array being an
 *   array of functions, each of thise functions must return promises but all of
 *   these promises will be executed asynchronously.  Each item in this
 *   top-level array will wait for the previous item.  If a returned promise
 *   fails the promise returned from this function will immediately fail.
 * @returns {Promise}
 *   One promise representing all of the underlying promises returned by the
 *   functions in the promiseMakers array.
 */
function getMultiPromise(promiseMakers) {
  return promiseMakers.reduce(function(prevPromise, promiseMaker) {
    return prevPromise.then(function() {
      return Array.isArray(promiseMaker)
        ? Promise.all(promiseMaker.map(function(subPromiseMaker) {
            return subPromiseMaker()
          }))
        : promiseMaker();
    });
  }, Promise.resolve());
}

~example~fail.js

// HIDE \\
console.load('local://getMultiPromise.js');

// HIDE \\
console.load('local://~example~test~functions.js');

// \\
getMultiPromise([
  succeedAfter(0.5),
  succeedAfter(0.4),
  [
    succeedAfter(1),
    succeedAfter(1),
    succeedAfter(1.3),
    succeedAfter(1.3),
    succeedAfter(1)
  ],
  failAfter(0.2),
  succeedAfter(0.1)
]).then(function(result) {
    console.log('DONE:', result);
  })
  .catch(function(result) {
    console.log('DONE (catch):', result);
  });

~example~fail~multi.js

// HIDE \\
console.load('local://getMultiPromise.js');

// HIDE \\
console.load('local://~example~test~functions.js');

// \\
getMultiPromise([
  succeedAfter(0.5),
  succeedAfter(0.4),
  [
    succeedAfter(1),
    failAfter(1),
    succeedAfter(1.3),
    succeedAfter(1.3),
    succeedAfter(1)
  ],
  succeedAfter(0.2),
  succeedAfter(0.1)
]).then(function(result) {
    console.log('DONE:', result);
  })
  .catch(function(result) {
    console.log('DONE (catch):', result);
  });

~example~succeed.js

// HIDE \\
console.load('local://getMultiPromise.js');

// HIDE \\
console.load('local://~example~test~functions.js');

// \\
getMultiPromise([
  succeedAfter(0.5),
  succeedAfter(0.4),
  [
    succeedAfter(1),
    succeedAfter(1),
    succeedAfter(1),
    succeedAfter(1),
    succeedAfter(1)
  ],
  succeedAfter(0.2),
  succeedAfter(0.1)
]).then(function(result) {
    console.log('DONE:', result);
  })
  .catch(function(result) {
    console.log('DONE (catch):', result);
  });

~example~test~functions.js

var getNextIter = (function(iter) {
  return function() {
    return ++iter;
  };
})(0);

function succeedAfter(secs) {
  return function() {
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        var msg = getNextIter() + ':  Success after ' + secs + ' second(s)';
        console.log(msg);
        resolve(msg);
      }, secs * 1e3);
    });
  }
}

function failAfter(secs) {
  return function() {
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        var msg = getNextIter() + ':  Failure after ' + secs + ' second(s)';
        console.log(msg);
        reject(msg);
      }, secs * 1e3);
    });
  }
}

Different tests in YourJS console:

• Succeed: https://www.yourjs.com/console/?gist=c5a579c823dae3f4162f4cd8450ea9c3&file=~example~succeed.js&skipIntro=1
• Fail: https://www.yourjs.com/console/?gist=c5a579c823dae3f4162f4cd8450ea9c3&file=~example~fail.js&skipIntro=1
• Fail on async part: https://www.yourjs.com/console/?gist=c5a579c823dae3f4162f4cd8450ea9c3&file=~example~fail~multi.js&skipIntro=1