JS шаблон цепочка обязанностей

chain_of_responsibility.js

var NO_TOPIC = -1;
var Topic;
 
function Handler(s, t) {
    this.successor = s || null; 
    this.topic = t || 0;
}
 
Handler.prototype = {
    handle: function () {
        if (this.successor) {
            this.successor.handle()
        }
    },
    has: function() {
        return this.topic != NO_TOPIC;
    }
};
 
var _handle = Handler.prototype.handle;
 
var app = new Handler({
    handle: function () {
        console.log('app handle');
    }
}, 3);
app.name = 'app';
 
var dialog = new Handler(app, 1);
dialog.handle = function () {
    //if (this.has()) {
    //} else {
        //console.log('dialog handle');
    console.log('dialog before ...')
    _handle.call(this);
    console.log('dialog after ...')
    //}
};
dialog.name = 'dialog';
 
var button = new Handler(dialog, 2);
button.handle = function () {
    //console.log('button handle');
    console.log('button before ...')
    _handle.call(this);
    console.log('button after ...')
};
button.name = 'button';
 
console.log(button)
 
button.handle();