IMO modern web language should have some notion of events as in my Sciter ( https://sciter.com/event-handling/ ) for example:

    event click $(table > thead > tr > th) {
      // click on table header cell
      // 'this' is that th element
    }

    class Widget : Element 
    {
       function attached() {...}

       event click $(span.up) { this.increment(); }
       event click $(span.down) { this.decrement(); }

       event mousedown { this.state.focus = true; } 
       ...
    }