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Describe the purpose and usage of the async and await keywords in modern JavaScript.

Sandra Emily16810-Oct-2023

Describe the purpose and usage of the async and await keywords in modern JavaScript.

javascriptjavascript asynchronous 
Updated on 11-Oct-2023
Sandra Emily

Sandra Emily

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Aryan Kumar

Aryan Kumar

11-Oct-2023

The async and await keywords in modern JavaScript are used to simplify asynchronous code, making it easier to read and maintain. They are part of the ECMAScript 2017 (ES8) specification and provide a more elegant way to work with Promises and asynchronous operations. Here's an explanation of their purpose and usage:

async Function:

  • Purpose: The async keyword is used to define asynchronous functions. It indicates that the function will always return a Promise, either explicitly or implicitly. It allows you to write asynchronous code in a more structured and synchronous-looking manner.
  • Usage: To declare an async function, you prepend the async keyword to the function declaration or expression:
async function fetchData() {
  // Asynchronous operations go here
}

await Operator:

  • Purpose: The await keyword is used within an async function to pause the execution of the function until a Promise is resolved. It allows you to work with Promises in a sequential, synchronous-like fashion, which can greatly enhance code readability.
  • Usage: To use the await keyword, you place it before a Promise, which you want to resolve before continuing the function's execution:
async function fetchData() {
  const response = await fetch('https://api.example.com/data');
  const data = await response.json();
  return data;
}

In this example, the await keyword is used with the fetch method and the json() method, allowing the code to wait for the response before processing it.

Error Handling: You can use try...catch blocks to handle errors when using await. If a Promise rejects, it will throw an exception that can be caught with catch:

async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    return data;
  } catch (error) {
    console.error('Error:', error);
  }

Using async and await, you can write asynchronous code that is more readable and resembles synchronous code flow, which makes it easier to understand and maintain. These keywords have become the standard for working with asynchronous operations in modern JavaScript.

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