Wednesday, August 5, 2009

JavaScript and DHTML Text Scroller with progress bar

You can find a wide variety of DHTML text scrollers on internet but I have created an easy to use scroller with a lot of flexibility and a progress bar. This is cross-browser compatible scroller and you can use multiple scrollers on the same page without assigning separate id’s to them.

Here are some benefits of using this DHTML scroller:
  • Zero coding required.
  • You can use multiple scrollers on a single page without assigning id’s separately.
  • Easily modifiable CSS layout and works with different styles for different scrollers on the same page.
  • Works with any mouse event giving you the flexibility of automatic and manual scrolling.
  • Cross-Browser compatibility.

JavaScript DHTML Scroller

Here are the sample scrollbar images (right click and save): up.png down.png

The scrolling function can be called from mouse over event for automatic scrolling or mouse down event for manual scrolling. The scrolling function is passed an object to the main container of the scroller and rest of the elements are navigated from there. This scroller code follows a strict hierarchy of div tags, so if you want to modify this and use your own styling and node hierarchy then you will have to change the JavaScript code to reach for the proper child nodes. For testing you can always use alert(element.className) to verify if you are navigating to the correct nodes. Instead of using the firstChild or childNodes functions from DOM, I have created my own function to get the child element nodes because when navigating using the DOM functions FireFox browser treats white spaces as text nodes and gives inconsistent results, for example to get to the third Element Node under the container you can use getElementChildNode(container, 2) (index starts at 0).

JavaScript Code:
<script type="text/javascript">
//Developed by: Abhinay Rathore |
var SPEED = 2; //scroll speed in pixels
//Starts the scrolling
function startScroll(container, dir, timer) {
    var scroller = getElementChildNode(getElementChildNode(container, 0), 0);
    clearInterval(scroller.timer); //clear existing timer
    //get Progress Column div id
    var progress_column = getElementChildNode(container, 2);
    var progress_style = getstyle(progress_column);
    var progress_bar = getElementChildNode(progress_column, 0); //get Progress bar id
    var progress_bar_style = getstyle(progress_bar); //get Progress bar style
    //calculate the Progress bar scrolling limit
    var progress_bar_limit = parseInt(progress_style.height.replace('px', '')) - parseInt(progress_bar_style.height.replace('px', ''));
    //get current top offset for the Progress bar (default 0px) = || '0px';
    var progress_bar_top = parseInt('px', ''));
    //calculate Scroll limit
    var limit = scroller.offsetHeight - scroller.parentNode.offsetHeight;
    //calculate Progress bar speed
    var progress_speed = (progress_bar_limit / (limit / SPEED));
    //create new object of Progress class
    progress = new Progress(progress_bar_limit, progress_speed, progress_bar_top);
    if (dir == -1) { // UP
        limit = 0;
        progress.limit = 0;
        scroller.timer = setInterval(function() { scrollUp(scroller, limit, progress_bar, progress) }, timer);
    else if (limit >= 0) // DOWN
        scroller.timer = setInterval(function() { scrollDown(scroller, limit, progress_bar, progress) }, timer);
function scrollUp(scroller, limit, progress_bar, progress) { // SCROLL UP
    var container = scroller.parentNode.parentNode; = || '0px';
    var top ='px', '');
    if (Math.abs(top) - limit <= SPEED) { //top end reached
        cancelScroll(container); = limit + 'px'; = Math.round(progress.getLimit()) + 'px';
    } else { = parseInt(top) + SPEED + 'px'; = Math.round(progress.getValue()) + 'px';
        progress.setValue(progress.getValue() - progress.getSpeed());
function scrollDown(scroller, limit, progress_bar, progress) { // SCROLL DOWN
    var container = scroller.parentNode.parentNode; = || '0px';
    var top ='px', '');
    if (limit - Math.abs(top) <= SPEED) { //botttom end reached
        cancelScroll(container); = '-' + limit + 'px'; = Math.round(progress.getLimit()) + 'px';
    } else { = top - SPEED + 'px'; = Math.round(progress.getValue()) + 'px';
        progress.setValue(progress.getValue() + progress.getSpeed());
// Cancel the scrolling on mouseout
function cancelScroll(container) {
    var scroller = getElementChildNode(getElementChildNode(container, 0), 0);
// Get Element Child node and specified index
// this is a fix for FireFox browser where firstChild and
// childNodes[] DOM functionalities don't work sometime
// as FireFox treats empty spaces as text nodes.
function getElementChildNode(node, index) {
    var element_node;
    var element_node_index = 0;
    var children = node.childNodes;
    for (var i = 0; i < children.length; i++) {
        if (children[i].nodeType == 1) {
            element_node = children[i];
            if (element_node_index == index) break;
            else element_node_index++;
    return element_node;
// Class for Progress bar
function Progress(limit, speed, value) {
    this.limit = limit;
    this.speed = speed;
    this.value = value;
    this.getLimit = function() { return this.limit; };
    this.getSpeed = function() { return this.speed; };
    this.getValue = function() { return this.value; };
    this.setValue = function(value) { this.value = value; };
// Get CSS Style properties
function getstyle(id) {
    var myStyle = id.currentStyle;
    if (navigator.appName == "Microsoft Internet Explorer")
        myStyle = id.currentStyle;
    else myStyle = document.defaultView.getComputedStyle(id, null);
    return myStyle;

I have used a very basic set of styling for the scrolling window. You can modify the CSS to match the color and styling for your website. Some of the things in the CSS should not be changed such as the relative positioning of the scroll_content and progress_bar div tags. If you wish to change the hierarchy under the scrolling container, make sure you pass the correct objects to the functions, for more help on the node hierarchy read the paragraph following the CSS code very carefully.

CSS Code:
<style type="text/css">
.container {
      height: 300px; width: 500px;
      border: 1px solid #000;
      padding: 5px;
.scroll_window {
      width: 475px; height: 300px;
      overflow: hidden; float: left;
      margin-right: 5px;
.scroll_content {
      position: relative;
      font-family: Verdana, Geneva, sans-serif;
      font-size: small; text-align: justify;
.up, .down {
      float: left; height: 20px; width: 20px;
.progress_column {
      float: left; height: 260px; width: 20px;
.progress_bar {
      height: 20px; width: 20px;
      position: relative;
      background-color: #CCC;

This scroller follows a strict hierarchy of div tags to make it a zero-coding tool. On mouse events, three arguments are passed to the startScroll function. First is the object to the main container from the image nodes by using DOM navigation function parentNode as this.parentNode.parentNode, second argument is the scrolling direction (-1 = up, 1 = down) and third argument is to set the scrolling speed. If your scrolling content is very large then you can set the scrolling speed to to higher number.

Here is the hierarchy of nodes in Scroller HTML DOM:
            |                 |____scroll_content
            |      |____img
            |                   |____progress_bar

You can have multiple copies of this scroller HTML code on your page without worrying about the calling function. The content for the scroller goes under the  scroll_content div tag.

HTML Code:
<div class="container">
    <div class="scroll_window">
        <div class="scroll_content">
            Your Content goes here!
<div class="up"><img onmouseover="startScroll(this.parentNode.parentNode, -1, 1)" onmouseout="cancelScroll(this.parentNode.parentNode)" src="up.png" alt="UP" /></div>
<div class="progress_column"><div class="progress_bar"></div></div>
<div class="down"><img onmouseover="startScroll(this.parentNode.parentNode, 1, 1)" onmouseout="cancelScroll(this.parentNode.parentNode)" src="down.png" alt="UP" /></div>

Feel free to use this DHTML scroller and modify it as you wish. But please do include a reference to my blog.

Technorati Tags: ,,


  1. mytectra placement Portal is a Web based portal brings Potentials Employers and myTectra Candidates on a common platform for placement assistance.

  2. Guaranteed #1 Search Engine Ranking Supreme Free Viral Traffic Join Now Get Millions Of Hits Free To Your Site/Blog!

    PornKings Adult Shopping Backlinks-Shopping Mega Store Legendary Stars As Stormy Daniels,Shawna Edwards,Jenna Jamison-New Adult Stars Movies,Adult Toys,Enhancers,Merchandise-More !

    Hits Express Rotator System Do You Need Visitors to Your Website or Affiliate Program? If your looking to gain more visitors to your website Hits Express is your answer. With our program your site is being shown to people all over the world 24/7 365 days a year!

    PAYDIR Free For All Forum Portal Search Engine Crawled Network PR10 Ranking Information Forum XXX!

    FreeLinkExchanges Be Seen In 12 Nations 312 Sites Over 30 Millions Viewers Monthly Buy Featured Link Now With 150 Search Engines Crawling The Network!

    How do I get guaranteed traffic? When someone signs up from your site, they must first click on your classified ad which will open a new window leading to your main website. They will have to wait a few seconds for the code to appear on a separate frame at the top of the screen reach millions free now!

    Blast Your Ad to Over 23,000 Opt-in Prospects at ShowMyLinks Submit Your Solo Email Ad to All Showmylinks Members GET YOUR TEXT LINK ADs LISTED 100% FREE FOR LIFE PLUS EARN MONEY TO YOUR PAYPAL!!

    Adult Store Empires Backlinks Resources Search Engine XXX!

    GET YOUR OWN MONEY-MAKING AD BOARD -- Integrating Text ad, Banner Ad and Email Ad into one Portal Make Money Fast With Your Paypal Reach Million Dollars In A Year Fast !

    Full Length Homemade Videos Watch real people's private home sex videos. Forget about those shitty 1-2 minute clips, these are all high quality full length videos! 40+ Bonus Sites You will also get full access to the entire reelpass network of sites which features over 40+ awesome movie sites, 1000's of movies and pictures to download! Download, Burn & Share Not only do you get to watch all our movies, you can also download every single one and save it forever, burn them to dvd or share with friends!!


Thanks a lot for your valuable comments :)