function handler() {
  console.log(1);
}

// es5

var obj = {
  handler: handler,
  toString: function (a) {
    return 'd ' + Object.prototype.toString.call(a);
  },
  prop_42: 42
};

// es6
var obj = {
  handler,
  toString(a) {
    return 'd ' + super.toString.call(a);
  },
  [ 'prop_' + (() => 42)() ]: 42 // prop_42: 42
};
