Get value in object from path as array of keys

valueFromPath.js

var obj = {
  a: {
    b: {
      c: 'yay'
    }
  }
};

var path = ['a','b','c'];

function valueFromPath (obj, arr) {
  var a = arr.slice(0);
  var key = a.shift();
  if (a.length) {
    return valueFromPath(obj[key], a);
  }
  return obj[key];
}

valueFromPath(obj, path);
// -> 'yay'