immutable

assign.js

function assingImmutable(obj, toAdd) {
  if (!_.isObjectLike(toAdd)) {
    return toAdd;
  }
  key = _.first(path);
  if (_.isArray(obj)) {
    copy = _.slice(obj);
    toAdd.forEach(function (value, idx) {
      copy[idx] = assingImmutable(obj[idx], value);
    });
    return copy;
  } else if (_.isObject(obj)) {
    copy = _.clone(obj);
    Object.keys(toAdd).forEach(function (key) {
      copy[key] = assingImmutable(obj[key], toAdd[key]);
    });
    return copy;
  } else {
    return toAdd;
  }
}