Timer.js

class Timer {
	constructor(func, time) {
		if (typeof func !== 'function') throw new Error('func is not a function');
		if (typeof time !== 'number') throw new Error('time is not a number');
		
		this.timerObj = setInterval(func, time);
		this.func = func;
		this.time = time;
	}
	
	stop() {
		if (this.timerObj) {
			clearInterval(this.timerObj);
			this.timerObj = null;
		}
		return this;
	}
	
	start() {
		if (!this.timerObj) {
			this.stop();
			this.timerObj = setInterval(this.func, this.time);
		}
		return this;
	}
	
	restart() {
		return this.stop().start();
	}
	
	changeTime(newTime) {
		if (typeof newTime !== 'number') throw new Error('newTime is not a number');
		this.time = newTime;
		return this.stop().start();
	}

    changeFunc(newFunc) {
        if (typeof newTime !== 'function') throw new Error('newFunc is not a function');
        this.func = newFunc;
        return this.stop();
    }

    executeFunc() {
        return this.func();
    }
	
}

module.exports = Timer;