How to use await and async in ES6?

In ES6, await and async are keywords used to handle asynchronous operations.

The async keyword is used to define an asynchronous function that returns a Promise object. For example:

async function fetchData() {
  // 异步操作
  return result;
}

The “await” keyword is used to wait for the result of an expression that returns a Promise object, which can be an asynchronous function call, a Promise object, or any expression that returns a Promise object. When using the “await” keyword, it needs to be placed within an async function. For example:

async function fetchData() {
  const result = await fetch('https://api.example.com/data');
  console.log(result);
}

In the above example, the fetchData function is an asynchronous function that waits for the result of the Promise object returned by the fetch function using the await keyword.

It is important to note that when using the await keyword, the code execution will pause until the asynchronous operation is completed and returns a result. This allows for writing asynchronous code in a synchronous manner when using the await keyword.

At the same time, the await keyword can only be used in an async function, otherwise an error will be thrown.

Furthermore, the expression following the await keyword can capture and handle errors of asynchronous operations, by using a try/catch statement to catch errors for error handling.

In summary, the ‘async’ keyword is used to define asynchronous functions, while the ‘await’ keyword is used to wait for the results of asynchronous operations, allowing asynchronous code to be written in a synchronous manner.