What is the purpose of the 'async' and 'await' keywords in JavaScript?

The async and await keywords in JavaScript are used for working with asynchronous code in a synchronous-like manner.

The async keyword is used to declare a function as asynchronous, which means that it will return a promise. Inside an async function, the await keyword can be used to pause the execution of the function until a promise is resolved. This allows you to write asynchronous code that looks and behaves more like synchronous code.

Here's an example of an async function that fetches data from an API using fetch() and returns a promise:

async function fetchData() {
  const response = await fetch('https://example.com/data');
  const data = await response.json();
  return data;

In this example, the fetch() method returns a promise that resolves to a Response object, which is then passed to response.json(), which also returns a promise that resolves to the parsed JSON data. By using await with each promise, the function will pause execution until each promise is resolved.

The await keyword can only be used inside an async function, and it can only be used with promises. If the promise is rejected, the await expression will throw an error, which can be caught with a try...catch block.

Using async and await can make asynchronous code easier to read and write, as it can eliminate the need for nested callbacks or promise chains. However, it's important to keep in mind that async functions still execute asynchronously, and they may not always be the best solution for all situations.