javascript autoscroll both ways

Question

I'm trying to setup a huge page that will slowly scroll down to the end of the page, and then going back to the top of the page, and so on... endlessly. I'm using the functions scrollBy()and setTimeOut() , which are doing fine the job, but I'm only able to manage a loop that go down and then it stops! Can you help me to add the code to go up, and repeat endlessly the scrolling down->up->down->up->... ?

Here's the script definition :

<script language="JavaScript">
function scrollAuto() 
  {
  window.scrollBy(0,1)
  setTimeout('scrollAuto()',1); 
  }

if (document.layers || document.all)
  { 
  scrollAuto() 
  } 
</script>

and here's how I call it ->

<body onLoad="scrollAuto();">

Thanks for your help.

Answer 1

this is what I came up with. The HTML is a little bit limited due to the snippet, so you can modify it to attach to the body, document, or window and use the "scrollBy" method if you prefer.

Remember to add the "resize" event so the scroll limit gets adjusted when the window resizes, otherwise you may run into problems.

Hope this helps.

 var scrollInfo = { speed: 2, timeout: 15 }; function initScroll() { //attachScroll(document.getElementById("scrolling-content")); attachScroll(); } function attachScroll(el) { if (el && el.scrollHeight) { scrollInfo.element = el; scrollInfo.max = el.scrollHeight - el.clientHeight; } else { var h = window.innerHeight || document.documentElement.clientHeight; scrollInfo.element = window; scrollInfo.max = document.documentElement.offsetHeight - h; } } function doScroll() { if (scrollInfo.element) { if (scrollInfo.element.scrollTop !== undefined) { var st = scrollInfo.element.scrollTop - scrollInfo.speed; if (st > 0 && st < scrollInfo.max) { scrollInfo.element.scrollTop = st; } else { scrollInfo.speed *= -1; } } else if (scrollInfo.element.scrollBy) { var st; if (scrollInfo.element.pageYOffset !== undefined) { st = scrollInfo.element.pageYOffset; } else if (scrollInfo.element.scrollY !== undefined) { st = scrollInfo.element.scrollY; } else { st = document.documentElement.scrollTop; } st += scrollInfo.speed; if (st > 0 && st < scrollInfo.max) { scrollInfo.element.scrollBy(0, scrollInfo.speed); } else { scrollInfo.speed *= -1; } } } }; function stopScroll() { window.clearInterval(scrollInfo.interval); } window.addEventListener("load", initScroll, false); window.addEventListener("resize", initScroll, false); scrollInfo.interval = window.setInterval(doScroll, scrollInfo.timeout);

 <div id="scrolling-content"> <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. <b>Lorem ipsum dolor sit amet, consectetur adipiscing elit</b>. Fusce nec tellus sed augue semper porta. Mauris massa. Vestibulum lacinia arcu eget nulla.</p> <p>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim lacinia nunc. Curabitur tortor. Pellentesque nibh. Aenean quam. In scelerisque sem at dolor. Maecenas mattis. Sed convallis tristique sem. <b>Vestibulum lacinia arcu eget nulla</b>. Proin ut ligula vel nunc egestas porttitor. <b>Curabitur tortor</b>. Morbi lectus risus, iaculis vel, suscipit quis, luctus non, massa. Fusce ac turpis quis ligula lacinia aliquet.</p> <p>Mauris ipsum. Nulla metus metus, ullamcorper vel, tincidunt sed, euismod in, nibh. Quisque volutpat condimentum velit. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Nam nec ante. <i>Curabitur tortor</i>. Sed lacinia, urna non tincidunt mattis, tortor neque adipiscing diam, a cursus ipsum ante quis turpis. Nulla facilisi. Ut fringilla. Suspendisse potenti. Nunc feugiat mi a tellus consequat imperdiet. Vestibulum sapien. Proin quam. Etiam ultrices.</p> <p>Suspendisse in justo eu magna luctus suscipit. Sed lectus. Integer euismod lacus luctus magna. Quisque cursus, metus vitae pharetra auctor, sem massa mattis sem, at interdum magna augue eget diam. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Morbi lacinia molestie dui. Praesent blandit dolor. Sed non quam. In vel mi sit amet augue congue elementum. Morbi in ipsum sit amet pede facilisis laoreet. Donec lacus nunc, viverra nec, blandit vel, egestas et, augue. <i>Mauris ipsum</i>. Vestibulum tincidunt malesuada tellus. Ut ultrices ultrices enim.</p> <p>Curabitur sit amet mauris. Morbi in dui quis est pulvinar ullamcorper. Nulla facilisi. Integer lacinia sollicitudin massa. <i>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos</i>. Cras metus. Sed aliquet risus a tortor. Integer id quam. Morbi mi. Quisque nisl felis, venenatis tristique, dignissim in, ultrices sit amet, augue. Proin sodales libero eget ante. Nulla quam. Aenean laoreet. Vestibulum nisi lectus, commodo ac, facilisis ac, ultricies eu, pede. Ut orci risus, accumsan porttitor, cursus quis, aliquet eget, justo.</p> <p>Sed pretium blandit orci. <i>Sed non quam</i>. Ut eu diam at pede suscipit sodales. Aenean lectus elit, fermentum non, convallis id, sagittis at, neque. Nullam mauris orci, aliquet et, iaculis et, viverra vitae, ligula. Nulla ut felis in purus aliquam imperdiet. Maecenas aliquet mollis lectus. <i>Integer lacinia sollicitudin massa</i>. Vivamus consectetuer risus et tortor. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. <b>Aenean lectus elit, fermentum non, convallis id, sagittis at, neque</b>. Sed cursus ante dapibus diam.</p> <p>Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta. Mauris massa. Vestibulum lacinia arcu eget nulla. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim lacinia nunc. Curabitur tortor. Pellentesque nibh. Aenean quam.</p> <p>In scelerisque sem at dolor. Maecenas mattis. Sed convallis tristique sem. Proin ut ligula vel nunc egestas porttitor. Morbi lectus risus, iaculis vel, suscipit quis, luctus non, massa. <i>Mauris massa</i>. Fusce ac turpis quis ligula lacinia aliquet. Mauris ipsum. Nulla metus metus, ullamcorper vel, tincidunt sed, euismod in, nibh. Quisque volutpat condimentum velit. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Nam nec ante. Sed lacinia, urna non tincidunt mattis, tortor neque adipiscing diam, a cursus ipsum ante quis turpis. Nulla facilisi.</p> <p>Ut fringilla. <i>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos</i>. Suspendisse potenti. Nunc feugiat mi a tellus consequat imperdiet. Vestibulum sapien. Proin quam. <i>Fusce ac turpis quis ligula lacinia aliquet</i>. Etiam ultrices. <b>Nulla facilisi</b>. Suspendisse in justo eu magna luctus suscipit. Sed lectus. Integer euismod lacus luctus magna. Quisque cursus, metus vitae pharetra auctor, sem massa mattis sem, at interdum magna augue eget diam. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Morbi lacinia molestie dui. Praesent blandit dolor. Sed non quam. In vel mi sit amet augue congue elementum.</p> <p>Morbi in ipsum sit amet pede facilisis laoreet. Donec lacus nunc, viverra nec, blandit vel, egestas et, augue. <i>Mauris ipsum</i>. Vestibulum tincidunt malesuada tellus. Ut ultrices ultrices enim. Curabitur sit amet mauris. Morbi in dui quis est pulvinar ullamcorper. Nulla facilisi. Integer lacinia sollicitudin massa. Cras metus. Sed aliquet risus a tortor. Integer id quam. Morbi mi. Quisque nisl felis, venenatis tristique, dignissim in, ultrices sit amet, augue. Proin sodales libero eget ante.</p> </div>

Edit: Updated to accept an element and fallback to window if not provided.

Note: If browser compatibility for old versions of IE is necessary, you may need to find other ways to calculate the innerHeight of a window and the window's scroll position.

Find the exact height and width of the viewport in a cross-browser way (no Prototype/jQuery)

Cross-browser method for detecting the scrollTop of the browser window

javascript autoscroll both ways

Question

1 answers

solution1
1 2015-01-31 01:19:18

javascript autoscroll both ways

Question

1 answers

solution1 1 2015-01-31 01:19:18

solution1
1 2015-01-31 01:19:18