deep search key/value structure and update a value, returning the modified object

deepUpdate.js

/*

var a = {
  b: {
    c: {
      d: false
    }
  }
};

deepUpdate("b.c.d", true, a) -> a.b.c.d === true

https://jsfiddle.net/h4mvptLb/
*/

function deepUpdate(dir, val, ref) {
  return (function loop(arr, val, i, obj, ref) {
    if (arr[i + 1])
      return loop(arr, val, (i + 1), obj[arr[i]], ref);
    if (!arr[i + 1]) {
      obj[arr[i]] = val;
      return {
        obj: ref,
        str: JSON.stringify(ref, null, 2)
      };
    }
  })(dir.split("."), val, 0, ref, ref)
}