Closure returning undefined unexpectedly

Question

I'm creating a melonJS game.

In my player entity - game.PlayerEntity = me.ObjectEntity.extend({, its update function checks for collision:

game.PlayerEntity = me.ObjectEntity.extend({
   var collision = me.game.collide(this); 

   if (collision) {
       if (collision.obj.type == me.game.ACTION_OBJECT) {
           console.log("NPCname: " + game.NPCEntity.init); //get settings from NPCEntity
       }
   }

Then in my NPC entity object, game.NPCEntity = me.ObjectEntity.extend ({, I want to return settings.name to the PlayerEntity above. So to do this I've created a closure returnSettings().

1) console.log(settings.name) outputs "Lee" as expected

2) return settings.name outputs "undefined"

Why is this?

game.NPCEntity = me.ObjectEntity.extend ({
    init : function(x, y, settings) {
        settings.image = "wheelie_right";
        settings.spritewidth = 64;
        settings.name = "Lee";
        this.parent(x, y, settings);

        this.collidable = true;
        this.type = me.game.ACTION_OBJECT;

        console.log(settings.name); //works
        console.log("returning... " + returnSettings()); //works

        //closure to return settings values externally
        function returnSettings () {
            return settings.name; //returns undefined when called by PlayerEntity above.
        }
    },

Thanks!

Answer 1

1. You shouldn't use a closure here
2. game.NPCEnity does not reference the instance, but the constructor function. If you set this.settings = … in the constructor function, you are creating a property on the instance.

You can access the instance with the this keyword inside your update function where you handle the collision, where it does point to the player.

To cite the tutorial:

// call by the engine when colliding with another object
// obj parameter corresponds to the other object (typically the player) touching this one
onCollision: function(res, obj) {…}

That means you can access the enemies settings by obj.settings inside that event handler.

---

If you're not using that handler but calling the collide method, from what I see the return value of that function has a .obj property which is presumably the collision target:

if (collision) {
    if (collision.obj.type == me.game.ACTION_OBJECT) {
        console.log("NPCname: " + collision.obj.settings.name); //get settings from NPCEntity
    }
}