How do I test asynchronous code in JavaScript?

How do I test asynchronous code in JavaScript?

You can use testing frameworks like Jest or Mocha, which support asynchronous testing with promises and async/await.

Can you show me an example using Jest?

Sure! Here's a simple example:

test('fetches data from API', async () => {
  const data = await fetchData();
  expect(data).toBeDefined();
});

What if I want to test multiple asynchronous calls?

You can use Promise.all to handle multiple asynchronous calls. Here's an example:

test('fetches multiple data from APIs', async () => {
  const [data1, data2] = await Promise.all([fetchData1(), fetchData2()]);
  expect(data1).toBeDefined();
  expect(data2).toBeDefined();
});

Are there any common pitfalls I should be aware of?

Yes, make sure to handle errors properly and avoid using done callback in async tests, as it can lead to confusion.