Scroll to bottom of div?

Question

I am creating a chat using ajax requests in rails and I'm trying to get a div to scroll to the bottom without much luck.

I am wrapping everything in this div:

#scroll {
    height:400px;
    overflow:scroll;
}

Is there a way to keep it scrolled to the bottom by default using JS?

Is there a way to keep it scrolled to the bottom after an ajax request?

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/

Answer 2

Using jQuery, scrollTop is used to set the vertical position of scollbar for any given element. there is also a nice jquery scrollTo plugin used to scroll with animation and different options (demos)

var myDiv = $("#div_id").get(0);
myDiv.scrollTop = myDiv.scrollHeight;

if you want to use jQuery's animate method to add animation while scrolling down, check the following snippet:

var myDiv = $("#div_id").get(0);
myDiv.animate({
    scrollTop: myDiv.scrollHeight
  }, 500);

Answer 3

small addendum: scrolls only, if last line is already visible. if scrolled a tiny bit, leaves the content where it is (attention: not tested with different font sizes. this may need some adjustments inside ">= comparison"):

var objDiv = document.getElementById(id);
var doScroll=objDiv.scrollTop>=(objDiv.scrollHeight-objDiv.clientHeight);                   

// add new content to div
$('#' + id ).append("new line at end<br>"); // this is jquery!

// doScroll is true, if we the bottom line is already visible
if( doScroll) objDiv.scrollTop = objDiv.scrollHeight;

Answer 4

var mydiv = $("#scroll");
mydiv.scrollTop(mydiv.prop("scrollHeight"));

Works from jQuery 1.6

https://api.jquery.com/scrollTop/

http://api.jquery.com/prop/

Answer 5

You can also, using jQuery, attach an animation to html,body of the document via:

$("html,body").animate({scrollTop:$("#div-id")[0].offsetTop}, 1000);

which will result in a smooth scroll to the top of the div with id "div-id".

Answer 6

Javascript or jquery:

var scroll = document.getElementById('messages');
   scroll.scrollTop = scroll.scrollHeight;
   scroll.animate({scrollTop: scroll.scrollHeight});

Css:

 .messages
 {
      height: 100%;
      overflow: auto;
  }