Introduction of async await

`async/await` is a syntactical feature in JavaScript that simplifies asynchronous programming. It provides a more readable and sequential way to write asynchronous code, making it easier to handle promises and perform asynchronous operations.

Traditionally, asynchronous operations in JavaScript were handled using callbacks or promises. However, managing multiple asynchronous operations with callbacks can lead to callback hell and make the code difficult to read and maintain. Promises introduced a better way to handle asynchronous operations, but they still required chaining `.then()` methods, which could result in complex and nested code structures.

`async/await` was introduced in ECMAScript 2017 (ES8) to address these issues and make asynchronous programming more intuitive. It is built on top of promises and allows you to write asynchronous code that resembles synchronous code, improving code readability and reducing the complexity of handling asynchronous operations.

Here’s a brief overview of how `async/await` works:

- The `async` keyword is used to define an asynchronous function. When a function is marked as `async`, it always returns a promise implicitly.
- Within an `async` function, you can use the `await` keyword to pause the execution and wait for a promise to resolve. The `await` expression can only be used inside an `async` function.
- When `await` is used, it suspends the execution of the function until the promise is resolved or rejected. It effectively allows you to write asynchronous code that looks and behaves like synchronous code.
- The value returned by the `await` expression is the resolved value of the promise. If the promise is rejected, an exception is thrown, which can be caught using a `try/catch` block.

Here’s an example that demonstrates the usage of `async/await`:

javascript
async function fetchData() {
 try {
 const response = await fetch('https://api.example.com/data');
 if (!response.ok) {
 throw new Error('Network response was not ok.');
 }
 const data = await response.json();
 console.log(data);
 } catch (error) {
 console.log('Error:', error);
 }
}
fetchData();

In this example, the `fetchData` function is marked as `async`, allowing the use of `await` inside it. The `await` keyword is used to pause the execution until the promise returned by `fetch` resolves. If the response is not successful, an error is thrown. Otherwise, the response is parsed as JSON using `await response.json()`, and the resulting data is logged to the console.

Overall, `async/await` simplifies asynchronous programming in JavaScript by providing a more concise and synchronous-like syntax for handling promises and asynchronous operations. It helps to eliminate callback hell and improves the readability and maintainability of code that involves asynchronous operations.