How to Keep a Div Scrolled to the Bottom in an Ajax Chat Application?

Scroll to Bottom of Div?

When building an interactive chat application using Ajax requests, a common challenge is ensuring that the messages div automatically scrolls to the bottom as new messages arrive. This article addresses two key questions related to this issue:

1. How to Keep Div Scrolled to Bottom by Default Using JavaScript?

To keep the div scrolled to the bottom without relying on user actions, use the following JavaScript code:

var objDiv = document.getElementById("your_div");
objDiv.scrollTop = objDiv.scrollHeight;

This code defines a variable objDiv to represent the element with the ID "your_div." It then sets the scrollTop property of this element to its scrollHeight. This effectively moves the scrollbar to the bottommost position.

2. How to Keep Div Scrolled to Bottom After an Ajax Request?

To maintain the desired scroll position even after an Ajax request, execute the JavaScript code from question 1 within the success callback function of the Ajax request. Here's an example:

$.ajax({
  url: "messages.php",
  success: function(data) {
    var objDiv = document.getElementById("messages");
    objDiv.scrollTop = objDiv.scrollHeight;
  }
});

In this example, when the Ajax request to "messages.php" succeeds, it updates the HTML content within the "messages" div. The subsequent JavaScript code adjusts the scroll position to the bottom of the div.

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