1.js

function promiseSome(promises) {
  var fulfills = [];
  var rejects = [];
  return promises.reduce(function(chain, promise) {
    return chain.then(function() {
      return promise;
    }).then(function(val) {
      fulfills.push(val);
    }, function(err) {
      rejects.push(err);
    });
  }, Promise.resolve()).then(function() {
    if (!fulfills[0]) throw Error("All failed");
    return fulfills;
  });
}

2.js

// With comments:

function promiseSome(promises) {
  // We're going to 'sort' promises into fulfilled & rejected values
  var fulfills = [];
  var rejects = [];
  // Using reduce to create a promise chain
  return promises.reduce(function(chain, promise) {
    // Wait for the last in the chain
    return chain.then(function() {
      // Wait for the current in the chain.
      // This has a nice side effect that it deals with values
      // in `promises` that are simple values rather than promises
      return promise;
    }).then(function(val) {
      // Store the success value
      fulfills.push(val);
    }, function(err) {
      // Store the failure
      // This also 'handles' the error in terms of the chain,
      // so the chain always fulfills with undefined
      rejects.push(err);
    });
  }, Promise.resolve()).then(function() {
    // Reject only if nothing fulfilled
    if (!fulfills[0]) throw Error("All failed");
    return fulfills;
  });
}