Javascript Async Await Explained

JavaScript is a single-threaded programming language, which means that it can only process one task at a time. However, with the rise of web applications and the need for more complex and dynamic features, JavaScript has had to adapt to handle multiple tasks simultaneously. Asynchronous programming is a way to work around JavaScript's single-threaded nature, and the async/await syntax is a way to make asynchronous code look and behave like synchronous code. This article will explain the async/await syntax in JavaScript and how it can be used to handle asynchronous tasks.

The async keyword is used to define an asynchronous function. An asynchronous function is a function that can contain asynchronous code, such as code that uses promises or callbacks. An asynchronous function returns a promise, which can be used to handle the function's result.

The await keyword is used to pause the execution of an asynchronous function until a promise is resolved. When the promise is resolved, the function continues to execute, and the result of the promise is returned. This allows the developer to write asynchronous code that looks like synchronous code, making it easier to read and understand.

For example, consider the following code that uses the setTimeout() function to simulate an asynchronous task:

function wait(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

async function example() {
  console.log("Start");
  await wait(2000);
  console.log("End");
}

example();

In this example, the example() function is defined as an asynchronous function. Inside the function, we use the await keyword to wait for the wait() function to finish. The wait() function returns a promise that resolves after a certain amount of time. When the promise is resolved, the example() function continues to execute and prints "End" to the console.

It's worth noting that the await keyword can only be used inside an async function. If you use await outside of an async function, JavaScript will throw an error.

Another important thing to note is that await only works with promises. If you try to await a non-promise value, JavaScript will treat it as if it's already resolved and the function will continue executing.

In conclusion, the async/await syntax in JavaScript is a way to handle asynchronous tasks in a more synchronous-like manner. It makes the code easier to read, write and understand. It's important to understand that it's a way to handle promises, and it can only be used inside an async function. It's a powerful tool that can help you handle complex asynchronous operations in a more elegant and manageable way.