XMLHttpRequest (XHR)

XMLHttpRequest (XHR) is a built-in browser API that allows client-side JavaScript to make HTTP requests to servers and retrieve data without refreshing the page. This functionality was a cornerstone of the AJAX (Asynchronous JavaScript and XML) revolution in the early 2000s, which enabled more dynamic and interactive web applications.

XHR can send and receive data in various formats—like XML, JSON, or plain text—and supports both synchronous and asynchronous modes. A typical use case might involve fetching user data from a server or submitting a form in the background.

Example (asynchronous):

javascript

const xhr = new XMLHttpRequest();
xhr.open('GET', '/api/data', true);
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    console.log(JSON.parse(xhr.responseText));
  }
};
xhr.send();

Despite its versatility, XHR is now less favored due to its verbose syntax and less intuitive promise handling compared to newer alternatives like the Fetch API, which offers a cleaner, promise-based interface.

Still, XHR is important historically and is supported in all browsers, making it useful for legacy systems or very specific use cases requiring fine-grained control over request states.

What is Superflex.ai?

Superflex.ai was built for teams that want to move fast without losing quality. Instead of pausing to spec things out, explain design decisions, or rebuild layouts from scratch, you can let Superflex do the heavy lifting. It delivers production-ready React code that mirrors your Figma designs—so designers and developers stay in sync, and progress never stalls.