Simple reoccurring timer

reoccurringtimer.js

var timer = function (waitTime, callBack, forever, start) {
    this.lastTime = Date.now();
    this.waitTime = waitTime;
    this.forever = forever;
    this.running = start;
    this.callBack = callBack;

    this.tick = function () {
        if (this.running) {
            if (Date.now() > this.lastTime + this.waitTime) {
                if(!this.forever){
                    this.running = false;
                }
                this.lastTime = Date.now();
                this.callBack();
            }
        }
    }

    this.start = function () {
        this.running = true;
    }
    
    this.stop = function(){
        this.running = false;
    }
};