In the development of web applications, it is common to encounter situations in which we need to perform asynchronous operations, such as making a request to a server or waiting for a response from a database. To handle this type of situation, JavaScript offers the keywords async y await, which allow us to write more readable and maintainable code.
What is asynchrony in JavaScript?
Asynchrony in JavaScript refers to the ability to perform tasks or execute code without blocking the main flow of the program. This means that we can continue executing other instructions while waiting for the result of an asynchronous operation.
Previously, JavaScript relied on the use of callbacks to handle asynchronous operations. However, this could lead to the creation of nested and poorly readable code, known as the callback hell. With the arrival of async/await in ES2017, async management became much simpler and more elegant.
The async keyword
The key word async It is used to declare an asynchronous function. This means that said function will contain asynchronous operations and can be paused at any time with the keyword await to wait for an operation to complete.
async function getData() { // Asynchronous code }
A function declared with the keyword async always returns a promise, even if it does not contain any asynchronous operations. This allows us to use the method .then() to handle the results of the asynchronous function.
The await keyword
The key word await is used to pause the execution of an asynchronous function until the operation to the right completes. The operation to the right of await must return a promise.
async function getData() { const response = await fetch('https://api.example.com/datos'); const data = await response.json(); return data; }
In the example above, we use await to wait for the API request to complete and obtain the data in JSON format. Once we have the data, we return it so that it can be used in other parts of the code.
Benefits of using async/await
The use of async/await It has several benefits:
- More readable code: By replacing callbacks with await, the code becomes more linear and easier to understand.
- Simplified error handling: With try/catch, we can easily handle errors that occur in asynchronous operations.
- Greater flow control: With await, we can pause function execution until an operation is completed, giving us greater control over the flow of the program.
Conclusion
In short, the use of async/await in JavaScript has revolutionized the way we handle async in our web applications. With these keywords, we can write more readable and maintainable code, avoiding the callback hell and simplifying error handling.
Frequently asked questions
When should I use async/await in JavaScript?
You must use async/await when you need to perform asynchronous operations sequentially and want more control over program flow. This is especially useful when working with API calls, database queries, or any other task that may take time.
How do I handle errors in an async function with async/await?
To handle errors in an asynchronous function, we can use try/catch. Inside the block try, we execute the asynchronous operations and in case an error occurs, we capture it in the block catch and we carry out the corresponding logic.
async function getData() { try { const response = await fetch('https://api.example.com/datos'); const data = await response.json(); return data; } catch (error) { console.log('An error occurred:', error); return null; } }
In the example above, we capture any errors that occur during the API request and display them in the console. If an error occurs, the function returns null.
What do I do if an asynchronous operation does not return a promise?
If an asynchronous operation does not return a promise, you can wrap it in a promise using the constructor Promise. This way, you can use await to pause the execution of the function until the operation completes.
async function asynchronousoperation() { return new Promise((resolve, reject) => { // Asynchronous code }); } async function myFunction() { await asynchronousOperation(); // Rest of the code }
In the previous example, asynchronousoperation() It doesn't return a promise, but we can wrap it in one using the constructor Promise to be able to use await.
I hope this article was helpful in understanding the use of async/await in JavaScript and how they can simplify async management in our applications. If you have any questions or suggestions, feel free to leave a comment or get in touch via our contact form at nelkodev.com/contact.
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