Scroll to bottom of div?

Question

I am creating a chat using Ajax requests and I\'m trying to get messages div to scroll to the bottom without much luck.

I am wrapping everything in this div:

Answer 1

I have encountered the same problem, but with an additional constraint: I had no control over the code that appended new elements to the scroll container. None of the examples I found here allowed me to do just that. Here is the solution I ended up with .

It uses Mutation Observers (https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver) which makes it usable only on modern browsers (though polyfills exist)

So basically the code does just that :

var scrollContainer = document.getElementById("myId");

// Define the Mutation Observer
var observer = new MutationObserver(function(mutations) {

  // Compute sum of the heights of added Nodes
  var newNodesHeight = mutations.reduce(function(sum, mutation) {
      return sum + [].slice.call(mutation.addedNodes)
        .map(function (node) { return node.scrollHeight || 0; })
        .reduce(function(sum, height) {return sum + height});
  }, 0);

  // Scroll to bottom if it was already scrolled to bottom
  if (scrollContainer.clientHeight + scrollContainer.scrollTop + newNodesHeight + 10 >= scrollContainer.scrollHeight) {
    scrollContainer.scrollTop = scrollContainer.scrollHeight;
  }

});

// Observe the DOM Element
observer.observe(scrollContainer, {childList: true});

I made a fiddle to demonstrate the concept : https://jsfiddle.net/j17r4bnk/