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I wrote this sticky div effect in Jquery but was wondering a way to do the same thing with vanilla javascript

.stick {
    position: fixed;
    top: 0;
}



$(document).ready(function () {  
  var top = $('#a8').offset().top;
  $(window).scroll(function (event) {
    var y = $(this).scrollTop();
    if (y >= top)
      $('#a8').addClass('stick');
    else
      $('#a8').removeClass('stick');

  });
});

I wrote this sticky div effect in Jquery but was wondering a way to do the same thing with vanilla javascript

.stick {
    position: fixed;
    top: 0;
}



$(document).ready(function () {  
  var top = $('#a8').offset().top;
  $(window).scroll(function (event) {
    var y = $(this).scrollTop();
    if (y >= top)
      $('#a8').addClass('stick');
    else
      $('#a8').removeClass('stick');

  });
});

• javascript
• jquery

Share Improve this question Follow asked Aug 28, 2014 at 16:00 Alex BorsodyAlex Borsody 2,06099 gold badges4545 silver badges7878 bronze badges

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3 Answers 3

Sorted by: Reset to default 5

Sure you can do the same in pure JS. Here is simple example:

var top = document.getElementById('a8').offsetTop;

window.onscroll = function() {
    var y = (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;
    if (y >= top) {
        a8.className = 'stick';
    }
    else {
        a8.className = '';
    }
};

Demo: http://jsfiddle/hd3uyf68/1/

Note, that in this simple example I don't actually implement addClass/removeClass functionality. If you need it it's quite easy to add.

In vanilla JavaScript:

function ready() {
    var box = document.getElementById('box'),
        top = box.offsetTop;

    function scroll(event) {
        var y = document['documentElement' || 'body'].scrollTop;

        if (y >= top) box.classList.add('stick');
        else box.classList.remove('stick');

    }

    window.addEventListener('scroll', scroll);
}

if (document.readyState == 'plete' || document.readyState == 'loaded') {
    ready();
} else {
    window.addEventListener('DOMContentLoaded', ready);
}

JSFiddle example:

http://jsfiddle/869fqgds/4/

Here is an adapted version from dfsq's answer, which is the most elegant and simple solution I've found so far:

    var myTop = document.getElementById('freeze').offsetTop;
    var origClass = freeze.className;
    window.onscroll = function() {
        var y = (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;
        if (y >= myTop) {
            freeze.className = origClass +' stick';
        }
        else {
            freeze.className = origClass;
        }
    };

// Note that I barely have javascript knowledge, so the modification, even if it works, might be far from optimal. I'm open to improvements.

Main differences are:

• variable name changed to avoid ambiguity (see ments of that answer).
• additional variable and modification inside if/else in order to allow using it with tags with an existing class already assigned.

The only issue remaining is that at the moment when the div is fixed, there is a kind of 'jump' in the flow. This is easily seen in the original jsfiddle if adding any text (for instance <p>See how I jump!</p>) a few lines below the div that is sticked.

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