Difference of using async / await vs promises?

JavaScript asynchronous operation: PROMISE and Async/AWAIT detailed explanation

Promise and Async/Await are two ways for JavaScript to process asynchronous operations. This article will explain their differences, advantages and applicable scenarios.

Promise

Definition:
1. Promise object represents the final completion (or failure) and the result value of the asynchronous operation. grammar:

Key features:

const fetchData = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve("数据已获取");
    }, 1000);
  });
};

fetchData()
  .then((data) => console.log(data))
  .catch((error) => console.error(error));

3. Use <理> to handle successful results.

Use <理> to deal with errors.

• You can use <链> chain call multiple asynchronous operations. .then()
• .catch() <势> Advantages:
• .then()

better than callback hell (

Chain calls are clearer than setting backward callbacks).
4. Use <明> for clear errors.

<挑> Challenge:
• .then()
• .catch() When many promise is processed, chain calls may still be difficult to read (called "Promise Hell").

When calling multiple

in the chain, the error treatment may require additional attention.
Async/Await

<义> Definition:
• Async/Await is based on Promise's syntax sugar, making the asynchronous code look more like a synchronous code. .then()
<法> grammar:

---

<键> Key features:

Use the <键> Keyword to declare the function of Promise.
2. Use <暂> to suspend execution until Promise is completed.
Use <理> to deal with errors.

const fetchData = async () => {
  try {
    const data = await new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve("数据已获取");
      }, 1000);
    });
    console.log(data);
  } catch (error) {
    console.error(error);
  }
};

fetchData();

3. Advantages:

Code readability: Compared with
• chain calls, the grammar is clearer and easy to understand. async
Easy to debug: Debugging tools allow you to execute ASYNC/AWAIT code single -step like synchronization code.
• await It is used for centralized errors.
• try...catch
Challenge:

4. It must be used in the function of statement.

If it is not handled in the circulation or sequence asynchronous calls, it may sometimes lead to obstruction.

• .then()
• When to use try...catch

Promise:

5. Used for simple disposable asynchronous operations.

When using libraries or APIs designed around Promise.

• When the chain calls multiple irrelevant operations. async
• Async/Await:

---

It is used to have multiple complex workflows that rely on asynchronous operations.

When you need clearer and easier code.

---

When debugging is important.

Combined

can be used in combination with Async/Await and Promise to achieve advanced use cases:

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