Experiment: Which API is more intention revealing?

es5-property-definition.js

function Game(){
  var total_score = 0;
  var scoring_map = {ghost: 10, pellet: 1, fruit: 5};

  Object.defineProperties(this, {
    score: { get: function(){ return total_score; } }
  });

  this.eat = function (edible){
    total_score += scoring_map[edible] ? scoring_map[edible] : 0;
  }
}

var pacman = new Game();

pacman.eat('ghost');
pacman.eat('fruit');

pacman.eat('pellet');
pacman.eat('pellet');
pacman.eat('pellet');
pacman.eat('pellet');

pacman.eat('not-in-scoring-map');

console.log('Score:', pacman.score); // 19

without-es5-properties.js

function Game(){
  // property + public accessor for (total score)
  var total_score = 0;
  this.score = function (){ return total_score; };

  // other properties
  var scoring_map = {ghost: 10, fruit: 5, pellet: 1};

  // public eat function (method)
  this.eat = function eat(edible){
    total_score += scoring_map[edible] ? scoring_map[edible] : 0;
  };
}

var pacman = new Game();

pacman.eat('ghost');
pacman.eat('fruit');

pacman.eat('pellet');
pacman.eat('pellet');
pacman.eat('pellet');
pacman.eat('pellet');

pacman.eat('not-in-scoring-map');

// This only works because the called function is a closure; so yes, the function totalScore() must be "applied" in order to retrieve the property value.
console.log('Score:', pacman.score()); // 19

The example sucks, I know :)

This gets really useful once Proxies are supported.

So, the non-es5 version has the benefit of not needed to use the new syntax; however, to me, it seems less intention revealing (though JavaScript veterans may be used to this nomenclature).

The es5 version seems to be obvious in intent. I also prefer "pacman.score" vs. "pacman.score()". I also dig the fact that I have control over which properties are enumerable (think: hasOwnProperty) vs. having to hack that in or play around with what goes on the "prototype" and what doesn't.

That being said...what say you?

Huh....funny to come back to this much later. I no longer feel the ES5 method is better. It's way more verbose for little/no value. Calling a function to get/set is actually fine.