Building a commenting system with AJAX and JavaScript

15 Sep 2023

In today’s digital age, interactive websites are becoming more and more popular. One of the key features of such websites is the ability for users to leave comments and engage with the content. In this blog post, we will discuss how to build a commenting system using AJAX and JavaScript.

What is AJAX?

AJAX, which stands for Asynchronous JavaScript and XML, is a technique used to make asynchronous requests to a server without refreshing the entire webpage. It allows us to update certain parts of a webpage dynamically without interrupting the user experience. By using AJAX, we can create a seamless commenting system that allows users to submit comments without any interruptions.

Implementing the Commenting System

To get started, we will need a basic HTML structure for our commenting system:

<!DOCTYPE html>
<html>
<head>
  <title>Commenting System</title>
</head>
<body>
  <div id="comments">
    <!-- Existing comments will be displayed here -->
  </div>

  <form id="comment-form">
    <textarea id="comment-input" placeholder="Enter your comment"></textarea>
    <button type="submit">Submit</button>
  </form>

  <script src="script.js"></script>
</body>
</html>

Here, we have a div with the id of “comments” which will hold the existing comments. Below that, we have a form with id “comment-form” that includes a textarea for users to enter their comments and a submit button.

Next, let’s implement the JavaScript code in script.js:

document.getElementById("comment-form").addEventListener("submit", function(event) {
  event.preventDefault(); // Prevent form submission

  var commentInput = document.getElementById("comment-input");
  var comment = commentInput.value;

  // Create a new AJAX request object
  var xhr = new XMLHttpRequest();

  // Set up the request
  xhr.open("POST", "/comments", true);
  xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

  // Handle the response
  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
      // Comment successfully submitted
      fetchComments(); // Refresh comments
      commentInput.value = ""; // Clear input field
    }
  };

  // Send the request
  xhr.send("comment=" + comment);
});

function fetchComments() {
  var xhr = new XMLHttpRequest();

  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
      var comments = JSON.parse(xhr.responseText);
      var commentsDiv = document.getElementById("comments");
      commentsDiv.innerHTML = ""; // Clear existing comments

      comments.forEach(function(comment) {
        var commentElement = document.createElement("div");
        commentElement.textContent = comment;
        commentsDiv.appendChild(commentElement);
      });
    }
  };

  xhr.open("GET", "/comments", true);
  xhr.send();
}

In this code, we first attach an event listener to the submit event of the comment form. We prevent the default form submission behavior and retrieve the comment entered by the user.

We then create a new AJAX request object and set up the request to send a POST request to the server with the comment data. On successful submission, we refresh the comments by calling the fetchComments function, and clear the comment input field.

The fetchComments function is responsible for retrieving the existing comments from the server and populating them in the “comments” div. It sends a GET request to the server and updates the comments div accordingly.

Conclusion

Using AJAX and JavaScript, we have successfully built a commenting system that allows users to submit and display comments without needing to refresh the entire webpage. This provides an enhanced user experience and promotes engagement on your website.

By leveraging the power of AJAX, we can create dynamic and interactive features that bring our websites to life. So go ahead and implement your own commenting system using these techniques and watch the user engagement soar! #AJAX #CommentingSystem