platform/video.videojs/dist/video.es.js
function assign(target) {
  for (var _len = arguments.length, sources = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
    sources[_key - 1] = arguments[_key];
  }

  if (Object.assign) {
    return Object.assign.apply(Object, [target].concat(sources));
  }

  sources.forEach(function (source) {
    if (!source) {
      return;
    }

    each(source, function (value, key) {
      target[key] = value;
    });
  });

  return target;
}
function assign(target) {
  for (var _len = arguments.length, sources = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
    sources[_key - 1] = arguments[_key];
  }

  if (Object.assign) {
    return Object.assign.apply(Object, [target].concat(sources));
  }

  sources.forEach(function (source) {
    if (!source) {
      return;
    }

    each(source, function (value, key) {
      target[key] = value;
    });
  });

  return target;
}
Object.assign-style object shallow merge/extend.

@param  {Object} target
@param  {Object} ...sources
@return {Object}