How to Cancel Previous AJAX Requests when Calling a New One

In modern web development, AJAX is commonly used to create asynchronous requests and retrieve data from a server. However, when multiple requests are made at the same time, it can lead to conflicts and unexpected results. To address this issue, it's important to cancel previous AJAX requests when calling a new one. This blog post will explain how to implement this functionality using JavaScript. We'll cover the basics of AJAX requests, how to cancel previous requests, and how to handle responses. By the end of this tutorial, you'll have a better understanding of how to manage AJAX requests effectively and avoid issues caused by concurrent requests.

Here's an example of how to cancel the previous AJAX request if a new one is called using JavaScript:

 let xhr = null;

function makeRequest() {
  // If an existing request is still processing, abort it
  if (xhr !== null) {
    xhr.abort();
  }
  
  // Create a new request
  xhr = new XMLHttpRequest();
  
  // Set up the request
  xhr.open('GET', 'https://example.com/data');
  
  // Send the request
  xhr.send();
  
  // Handle the response
  xhr.onreadystatechange = function() {
    if (xhr.readyState === XMLHttpRequest.DONE) {
      if (xhr.status === 200) {
        console.log(xhr.responseText);
      } else {
        console.log('Request failed');
      }
    }
  }
}

In this example, we first check if xhr is not null. If it's not, it means there's an existing AJAX request in progress, so we call the abort() method to cancel it.

We then create a new AJAX request using XMLHttpRequest(). After setting up the request, we call the send() method to send it. Finally, we handle the response using the onreadystatechange event.

By calling abort() on the previous request, we ensure that only one AJAX request is being processed at any given time. This helps prevent conflicts and ensures that the correct response is received