It will only disable entity, as DOM elements are independent and separate from entities. Regardless of where JS code is written, there is no relationship of states between DOM and Entities - you have to simply subscribe to enable/disable events on script of that entity, and set style.display = 'none' on DOM elements you want to hide. Or some style class alterations on some parent DOM element and handle display: none in CSS.
Uimanager.prototype.onMenuBtnPressed = function (event)
{
// how to access the style of the entity / element I have ?
// this.menu.style.display = ‘none’ ? since such a thing doesn’t exist
};