Instance vs Prototype definitions

instance_v_proto.js

/**
 *  don't know how to use prototype style class defs.  It's possible to use method.apply to infer scope,
 *  however it gets complicated when using 3rd party libs and passing a cb function as a parameter.
 *  I've seen context wrappers that do this, but it seems overly complicated when I can just use instance style
 */

function InstanceStyleTest() {
    var self = this;

    this.methodA = function() {
        // calling direct - both methods work
        // this is instance scope, and self is in scope, so self == this
        this.success("this");
        self.success("self");
    }

    this.methodB = function() {
        setInterval(this.methodC, 1000);
    }

    this.methodC = function() {
        // Doesn't work - our scope is now the Window, so this no longer points to the instance
        // this.success();

        // Does work - even though we're scoped outside the class, we appear to be in a closure,
        // so going up the chain, we find self
        self.success("self as callback");
    }

    this.success = function(from) {
        console.log("Success from " + from );
    }

}



function PrototypeStyleTest() {
    var self = this;
}

PrototypeStyleTest.prototype.methodA = function() {
    this.success("this"); // this works since this is in scope
    //self.success(); // but this doesn't -- since we don't go up the chain in prototype I assume

    //console.log(this); // this correctly points to this instance (I think...or is it to the prototype?)
    //console.log(self); // apparently self is window?
}

PrototypeStyleTest.prototype.methodB = function() {
    setInterval(this.methodC, 1000);
}

PrototypeStyleTest.prototype.methodC = function() {
    // Doesn't work - our scope is now the Window, so this no longer points to the instance
    this.success("this as callback");

    // Doesn't work either - since self never worked in this design pattern in the first place
    self.success("self as callback");
}

PrototypeStyleTest.prototype.success = function(from) {
    console.log("Success from " + from );
}


var instStyle = new InstanceStyleTest();
console.log("-- Instance Style --");
instStyle.methodA();
instStyle.methodB();

var protoStyle = new PrototypeStyleTest();
console.log("-- Prototype Style --");
protoStyle.methodA();
protoStyle.methodB();