Note : I am using jQuery
You can use the scrollTop property to track the scrolling of the document.
$(".className")[0].ownerDocument.scrollingElement.scrollTop
and then used the disabled attribute to disable the button.
$("button").attr("disabled","");
Below is the complete code to test how it works.
Run the snippet.
var pageTopPosition = $(".long-page")[0].ownerDocument.scrollingElement.scrollTop;
setInterval(function() {
if (pageTopPosition != $(".long-page")[0].ownerDocument.scrollingElement.scrollTop) {
$("button").attr("disabled", "");
} else {
$("button").removeAttr("disabled");
}
pageTopPosition = $(".long-page")[0].ownerDocument.scrollingElement.scrollTop;
}, 100);
.long-page {
height: 2000px;
}
.popup {
width: 100%;
background-color: #FFEFD5;
color: red;
text-align: center;
position: fixed;
top: 0;
font-size: 1.5em;
padding: 15px;
}
<div class="long-page">
</div>
<div class="popup">
<button>My Button</button>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>