object edit

objEdit.js

function edit(obj, key, value) {
  if (!key) return obj;

  var keys = key.split('.');
  
  return keys.reduce(function (prev, next, i) {
    if (keys.length === i + 1 && value !== undefined) {
      prev[next] = value;
      return obj;
    } else {
      return prev[next];
    }
  }, obj);
}