Promise.sequential

gistfile1.js

Promise.sequential = function(runnables) {
  return new Promise(function(resolve, reject) {
    var results = [];

    runnables.reduce(function(sequence, aRunnable) {
      return sequence.then(function() {
        return aRunnable.run();
      }).then(function(data) {
          results.push(data);
          if (results.length === runnables.length) {
            resolve(results);
          }
      });
    }, Promise.resolve());
  });
}