//Handler
function Rescuer(code, next) {
    this._code = code;
    this._next = next;

    //HandleRequest()
    this.help = function(code) {
        if (this._code === code) {
            this.toHelp();
        } else if (next != undefined) {
            next.help(code);
        }
    }
}

//ConcreteHandler
function Firefighter(next) {
    Rescuer.apply(this, [1, next]);

    this.toHelp = function() {
        console.log("call firefighters");
    }
}

//ConcreteHandler
function Police(next) {
    Rescuer.apply(this, [2, next]);

    this.toHelp = function () {
        console.log("call the police");
    }
}

//ConcreteHandler
function Ambulance(next) {
    Rescuer.apply(this, [3, next]);

    this.toHelp = function () {
        console.log("call an ambulance");
    }
}

var ambulance = new Ambulance();
var police = new Police(ambulance);
var firefighter = new Firefighter(police);
firefighter.help(1);
//printed: call firefighters
firefighter.help(2);
//printed: call the police
firefighter.help(3);
//printed: call an ambulance