interface EventEmitter<T extends Function> {
    on: T;
}

type MouseType = 'mousedown' | 'mouseup';
type TouchType = 'touchstart' | 'touchend';
type MouseOn = (m: MouseType, e: (e: MouseEvent) => void) => void;
type TouchOn = (m: TouchType, e: (e: TouchEvent) => void) => void;
let noop: any = () => { };

class AABB implements EventEmitter<MouseOn&TouchOn> {
    on: MouseOn & TouchOn = noop;
}

let aabb = new AABB();

aabb.on('mousedown', (param: MouseEvent) => {

})
aabb.on('touchstart', (param: TouchEvent) => {

})
aabb.on('mousedown', (param: TouchEvent) => {

})