clockClass.js

class Clock {
    constructor({template}) {
        this.template = template;
    };

    render(){
        let date = new Date();

        let hours = date.getHours();
        if(hours < 10) hours = '0'+hours;

        let mins = date.getMinutes();
        if(min < 10) mins = '0'+mins;

        let secs = date.getSeconds();
        if(sec < 10) sec = '0'+sec;

        let output = this.template
        .replace('h',hours)
        .replace('m',mins)
        .replace('s',secs);

        console.log(output);
    };

    stop(){
        clearInterval(this.timer);
    }

    start(){
        this.render();
        this.timer = setInterval(()=> this.render(),1000);
    }

}


class ExtendedClock extends Clock {
    constructor(options){
        super(options);
        let {precision = 1000 } = options;
        this.precision = precision;
    }

    start() {
        this.render();
        this.timer = setInterval(()=>this.render(),this.precision);
    }
}