RPG Maker Forums

Hello!


I am having some trouble trying to understand javascript's constructors and prototypes.


For example, here there is some code extracted from the engine:


// Scene_Map
//
// The scene class of the map screen.

function Scene_Map() {
this.initialize.apply(this, arguments);
}

Scene_Map.prototype = Object.create(Scene_Base.prototype);
Scene_Map.prototype.constructor = Scene_Map;

Scene_Map.prototype.initialize = function() {
Scene_Base.prototype.initialize.call(this);
this._waitCount = 0;
this._encounterEffectDuration = 0;
this._mapLoaded = false;
this._touchCount = 0;
};


I'll try to explain what I currently understand: first it creates the object Scene_Map. Then, inside the constructor (I'm calling constructor to anything that is inside the brackets in "function Scene_Map()", please correct me if I'm wrong) the intialize function later declared is called by this.initialize.apply(this, arguments). Then, the prototype of the object Scene_Base is passed onto the protoype of the object Scene_Map, thus inheriting its properties.


(I am aware what I've said could be utterly wrong, but describing how I read this code might help you to understand what I don't)


I always thought the prototype of a object was the same as the constructor, but apparently, I'm wrong.


For instance, I have no idea what is happening here: 


Scene_Map.prototype = Object.create(Scene_Base.prototype);
Scene_Map.prototype.constructor = Scene_Map;


And also, why you can't put everything that there is on Scene_Map.prototype.initialize inside the constructor of Scene_Map? Like this:


function Scene_Map() {
function initialize() {
Scene_Base.prototype.initialize.call(this);
this._waitCount = 0;
this._encounterEffectDuration = 0;
this._mapLoaded = false;
this._touchCount = 0;
};




As you can see, there is a lot I don't know. I would be really thankful if someone could help me to understand how prototypes and constructors work, what they truly are, and in what they differ.


Thanks!