Set value at string path of object

gistfile1.js

// Set a value at a string-designated path.
//
// Takes an object to be modified, a string path ('a.b') and a value to be set
// at that path.
//
// Returns the modified object (although the changes are made in place)
var set = function (obj, path, val) {
  if (!obj || typeof obj !== "object") return obj;
  if (!path || typeof path !== 'string') return obj;
  var keys = path.split('.'),
      level = obj;
  keys.forEach(function (key, i) {
    var last = (i === keys.length - 1);
    if (last) return level[key] = val;
    if (!level[key] ||
        typeof level[key] !== "object") level[key] = {};
    level = level[key];
  });
  return obj;
};