How can you test asynchronous code in JavaScript?

To test asynchronous code in JavaScript, you can use testing frameworks like Jest or Mocha. These frameworks provide built-in support for handling asynchronous operations. You can use async/await or return promises in your test functions. For example, in Jest, you can write:

test("fetches data successfully", async () => {
  const data = await fetchData();
  expect(data).toBeDefined();
});

Alternatively, you can use callbacks and the done function to signal the end of an asynchronous test.