JSFiddle - React, Tailwind, and code Playground

JavaScript

class Timer {
	
  constructor() {
  	
    let self = this;
    
    this.timer = setInterval(function() {
    	self.update();
    }, 1000);	
  }
  
  update() {
			
     $(this).trigger('timer-tick');
	}
}

class DigitalTimer {
	
  constructor() {
  	
    this.timer = new Timer();
    
    $(this.timer).on('timer-tick', function() {
   		console.log('yes'); 
    });
  }
}

const digitalTImer = new DigitalTimer();