Build object from string.

build_object.js

function build(o, p, v){
  var k=[],l,m;
  while (m=/(\w+)\.?/g.exec(p)) k.push(m[1]);
  for (var i=0; i<k.length; i++) {
    l=o;
    o=o[k[i]];
  }
  if (v) l[k[k.length-1]]=v;
  return v || o;
}

gistfile2.js

var test = {a: {b: {c: "lol"}}};

build(test, "a.b.c"); // Returns "lol"
build(test, "a.b.c", "seventeen"); // Sets test.a.b.c to "seventeen" and returns "seventeen"