在打字稿中为 lit 元素组件添加事件侦听器

Question

I've successfully added an eventlistener for my Lit element component inside my Typescript code:

async firstUpdated() {
  await this.updateComplete;

  // Add an event listener to our event-search component so we can switch the current event
  const eventSearch = document.querySelector('event-search');
  if(typeof eventSearch !== 'undefined') {
    eventSearch.addEventListener('select', this.changeCurrentEvent);
  }
}

async changeCurrentEvent(event) {
  await this.fetchTickets(event.id);
  this.currentEvent = event;
}

async fetchTickets(eventId: number) {
  try {
    this.tickets = await fetchData(ticketEndpoint(eventId))
  } catch (error) {}
}

However, when executing the event i get the following error:

Uncaught (in promise) TypeError: this.fetchTickets is not a function at HTMLElement.<anonymous>

Apparently it does land in the changeCurrentEvent function but it cannot find the fetchTickets function.

Answer 1

You can use ES6 Arrow Function syntax to avoid having to write this.changeCurrentEvent.bind(this) .

changeCurrentEvent = async (event) => {
  await this.fetchTickets(event.id);
  this.currentEvent = event;
}