Union Types For Logging Events

union.ts

enum EventType {
  SEARCH,
  PROFILE_UPDATE,
  CART_UPDATE
}

type Event = 
  | {type: EventType.SEARCH; query: string}
  | {type: EventType.PROFILE_UPDATE; fields: string[]}
  | {type: EventName.CART_UPDATE; newSubtotal: number; oldSubtotal: number}
  ;

function logEvent(event: Event) {
  switch(event.type) {
    case EventType.SEARCH:
      return handleSearchEvent(event);
    case EventType.PROFILE_UPDATE:
      return handleProfileUpdateEvent(event);
    case EventType.CART_UPDATE:
      return handleCartUpdateEvent(event);
    default:
      throw enforceExhaustive(event.type)
  }
}