slice.js

function slice(object, keys) {
  return keys.reduce(function(results, key) {
    if (object.hasOwnProperty(key)) {
      results[key] = object[key];
    }
    return results;
  }, {});
}

var h = { a: 1, b: 2, c: 3 };

var results = slice(h, ['a', 'b']);

console.log(results);