bus.js

class BusEvents {
  on(event, fn){}
  emit(event, ...data){}
}

class JQueryBusEvents extends BusEvents{
  constructor($=window.jQuery){
    super();
    this.$doc = $(document);
  }
  on(event, fn) {
    this.$doc.on(event, fn)
  }
  
  emit(event, ...data){
    this.$doc.trigger.apply(this.$doc, [event].concat(data));
  }
}

window.bus = new JQueryBusEvents();


////// En la modal
window.bus.on('close-modal', function(){/*Aqui cierro la modal*/});


//// En otra parte de tu código
$('#button-id').on('click', function(){
  window.bus.emit('close-modal');
});