How do I make an HTTP request in Javascript?

Making HTTP requests is a common task in web development. In Javascript, you can make HTTP requests using the built-in ‘XMLHttpRequest‘ object or the newer ‘fetch()‘ method. In this article, we’ll cover both methods and discuss their advantages and disadvantages.

Using XMLHttpRequest

XMLHttpRequest (XHR) is a built-in object in Javascript that enables you to send HTTP requests and receive responses from a server. Here’s an example of how to use it:

const xhr = new XMLHttpRequest();
xhr.open('GET', 'https://jsonplaceholder.typicode.com/users');
xhr.onload = function() {
  if (xhr.status === 200) {
    console.log(JSON.parse(xhr.responseText));
  } else {
    console.error('Request failed.  Returned status of ' + xhr.status);
  }
};
xhr.send();Code language: JavaScript (javascript)

In the code above, we create a new ‘XMLHttpRequest‘ object and call the ‘open()‘ method to initialize a new HTTP request. The first argument is the HTTP method, which in this case is ‘GET‘. The second argument is the URL we want to send the request to.

After we’ve opened the request, we set the ‘onload‘ event handler to a function that will be called when the server responds. In this case, we’re checking the response status to make sure it’s ‘200‘ (OK), and then we’re parsing the response text as JSON and logging it to the console.

Finally, we call the ‘send()‘ method to send the HTTP request.

Advantages of XMLHttpRequest

One advantage of using ‘XMLHttpRequest‘ is that it’s been around for a long time and is widely supported in all modern browsers. Additionally, it gives you more control over the HTTP request, such as setting custom headers, and it supports sending and receiving binary data.

Disadvantages of XMLHttpRequest

One disadvantage of ‘XMLHttpRequest‘ is that it requires more boilerplate code than other methods. Additionally, it doesn’t support promises natively, which can make it harder to work with in modern Javascript applications.

Using fetch()

‘fetch()‘ is a newer Javascript method for making HTTP requests that was introduced in ES 2015. It uses promises to handle asynchronous requests and responses. Here’s an example of how to use ‘fetch()‘:

fetch('https://jsonplaceholder.typicode.com/users')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error(error));Code language: JavaScript (javascript)

In this code, we call ‘fetch()‘ with the URL we want to send the request to. This returns a promise that resolves to the Response object representing the server’s response.

We then call the ‘json()‘ method on the Response object to parse the response as JSON. This returns another promise that resolves to the parsed JSON data.

Finally, we log the parsed data to the console, and catch any errors that occur.

Advantages of fetch()

One advantage of ‘fetch()‘ is that it’s a newer, more modern method for making HTTP requests, and it uses promises, which are easier to work with in modern Javascript applications. Additionally, it’s simpler to use than ‘XMLHttpRequest‘, requiring less boilerplate code.

Disadvantages of fetch()

One disadvantage of ‘fetch()‘ is that it’s not supported in older browsers, such as Internet Explorer. Additionally, it doesn’t provide as much control over the HTTP request as ‘XMLHttpRequest‘, such as setting custom headers.

Conclusion

In conclusion, there are two main methods for making HTTP requests in Javascript: ‘XMLHttpRequest‘ and ‘fetch()‘. Both have their advantages and disadvantages, and the choice of which to use will depend on the specific requirements of your application.

If you need more control over the HTTP request, or need to send and receive binary data, ‘XMLHttpRequest‘ may be the better choice. If you’re working with modern Javascript applications and want a simpler, promise-based method for making HTTP requests, ‘fetch()‘ is a good choice.

Regardless of which method you choose, it’s important to handle errors and ensure that your application is secure by properly validating and sanitizing any user input.