Async/Await in JavaScript: Simplifying Asynchronous Code
Async/await is a feature of JavaScript that simplifies asynchronous programming. We will define async/await, describe how it functions, and give some practical examples in this blog article.
Understand Asynchronous Programming
Asynchronous programming is a programming pattern where tasks are completed simultaneously and the results are returned as soon as they are ready. Traditional synchronous programming executes tasks sequentially, which might cause the user to wait a very long time.
Javascript offers asynchronous programming in primarily three different ways: callbacks, promises, and async/await.
Callbacks are functions that are executed after a task is completed and are passed as arguments in other functions. Promises are objects that stand in for values that might not be available right away but will be fulfilled eventually. Async/await is a modern method for managing asynchronous programming that makes the code syntax simpler and more readable.
I recommend to read JavaScript Promise before delving into Async/await for a better understanding of the underlying concepts.
What is Async/Await?
Programmers can write asynchronous code more synchronously using JavaScript’s async/await syntax feature. It is based on Promise and offers a cleaner, more legible approach to construct asynchronous programmes.
When a function is marked with the “async” prefix, it means that it will always return a Promise. The “await” keyword is used to halt the execution of the programme inside an async function until the Promise is fulfilled.
How to use Async/Await?
let’s look at an example to understand working of async/await. Consider the case where a function returns a Promise that resolves after some time:
function wait(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}We can use this function to create a delay in our code. For instance, We can delay the execution of the function by one second by using the code below:
async function delayedFunction() {
await wait(1000);
console.log("Delayed function executed");
}In this code, we have marked the “delayedFunction” as asynchronous using the “async” keyword. We have also used the “await” keyword to pause the execution of the code until the Promise returned by “wait” function is resolved. Once the Promise is resolved, the console will log the message “Delayed function executed”.
Handling Errors with Async/Await
Error handling is simplified when async/await is used, which is one of its advantages. We can use the “try/catch” to handle the error in a more synchronous way. For instance, that we have a function that returns a Promise which expires after some time:
function waitAndReject(ms) {
return new Promise((resolve, reject) => setTimeout(() => reject("Error"), ms));
}We can use this function to simulate an error in our code. For example, we can handle the error in the following way:
async function errorFunction() {
try {
await waitAndReject(1000);
} catch (e) {
console.log(e);
}
}In this code, we have used the “try/catch” statement to handle the error thrown by the Promise returned by “waitAndReject”. If the Promise is rejected, the error message “Error” will be logged to the console.
Real-world Examples of Async/Await
Let’s take a look at how to use async/await with the Fetch API to retrieve data from a third-party API:
async function getJokes(category) {
try {
const response = await fetch(`https://api.chucknorris.io/jokes/random?category=${category}`);
const data = await response.json();
const joke = data.value;
console.log(`Here's a joke about ${category}: ${joke}`);
} catch (e) {
console.log(`Error: ${e}`);
}
}In this code, we have used async/await with the Fetch API to make an HTTP request to the Chuck Norris Jokes API and retrieve a random joke for a given category. We have also used try/catch to handle any errors that may occur during the request.
The Chuck Norris Jokes API is a public API that provides random jokes about Chuck Norris in different categories such as “dev”, “science”, “movie”, etc. This example demonstrates how to use async/await to retrieve data from a third-party API and use it in your application.
Benefits of Using Async/Await
Using async/await has several benefits over traditional asynchronous programming methods. First, it simplifies the syntax and makes the code more readable by avoiding callback nesting and chaining. Second, it allows for better error handling by using try/catch blocks to handle exceptions. Finally, it improves the performance of web applications by allowing tasks to execute concurrently and reducing the wait time for the user.
Best Practices for Using Async/Await
While async/await provides a simpler and more concise way to write asynchronous code, there are still some best practices to keep in mind. Here are a few tips to help you write efficient and maintainable async/await code:
- Always use
try/catchblocks to handle exceptions and errors. - Use
Promise.all()method to execute multiple asynchronous tasks concurrently. - Use
Promise.race()method to execute multiple asynchronous tasks and return the result of the first task that resolves or rejects. - Avoid using
awaitinside loops, as it can block the execution of other tasks. - Use third-party libraries such as
asyncorbluebirdto handle complex asynchronous tasks.
In conclusion, JavaScript’s async/await functionality is a potent tool that lets programmers write asynchronous code in a more synchronous manner. It makes handling Promise easier and makes handling errors simpler. It could take some time to become used to the syntax and comprehend how async/await functions if you are a beginner. But once you get the hang of it, you’ll discover that writing asynchronous JavaScript code gets much simpler and more pleasurable.
Some Quick Links
JsFramework | CleanCode | LocalStorage | Redis Caching | Node.js Cluster | Array Methods | Callback Function | Promise | Async/Await
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