Here, in this article, we will learn how to prevent the body from scrolling when a modal or a pop-up is opened using JavaScript.
Table of Contents
The scroll event is not cancelable. So, we cannot just disable scroll in our website using CSS or using an eventListener. However, we can use the mousewheel and wheelevent, to stop the scroll on our webpage when the modal is opened.
What is a wheel event in JavaScript?
A wheel event is triggered whenever the user rotates the wheel button or a pointing device (usually a mouse) to navigate through the web page.
NOTE : A wheel event is different from a scroll event. The action of a wheel event is implementation specific and it does not dispatch a scroll event.
scrollevent fires when the user scrolls any element using mouse or arrow keys or scrollbar.
wheelevent fires only when mouse-wheel is use.
In this article, we will see an example where the default scroll of the body is disabled when a modal or a pop-up is opened.
Prevent Scrolling when modal is opened
First, we will code our HTML page, here I have a div with id modal-wrapper and inside it we have another div with id modal-body . This is the main body of the modal. And I have a button called Open Modal with a on click event.
HTML code :
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>repl.it</title>
<link href="style.css" rel="stylesheet" type="text/css" />
<link rel="stylesheet" href="./style.css">
</head>
<body>
<div id="content">
<button onclick="openModal()">Open Modal</button>
<div id="modal-wrapper">
<div id="modal-body">
<p>This is a modal</p>
<button onclick="closeModal()">Close Modal</button>
</div>
</div>
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</div>
<script src="main.js"></script>
</body>
</html>style.css :
body,
html{
margin: 0;
padding: 0;
font-size: 50px
}
#modal-wrapper{
display: none;
position: fixed;
top: 0;
right: 0;
left: 0;
right: 0;
width: 100%;
height: 100%;
background-color: rgba(0, 0, 0, 0.116);
text-align: center;
}
#modal-body{
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
width: 400px;
height: 300px;
background-color: seashell;
}
.active-modal{
display: block !important;
}
#content {
background: white;
height: 3000px;
}Here the #modal-wrapper is fixed and display: none by default. And it also have .active-modal class which will be added when the user clicks the button. The active-modal class has the property of display:block, to make the modal visible on the web page.
main.js :
var modal = document.getElementById('modal-wrapper');
modal.addEventListener('wheel', function(e) {
e.preventDefault();
}, false);
function openModal(){
fixed.classList.add("active-modal");
}
function closeModal(){
fixed.classList.remove("active-modal");
}In the main.js file, all I have done is add a wheel event listen to #modal-wrapper, and then disable its default behavior. So now when anyone tries to use the mouse wheel to scroll the page the scroll will be disabled.
And it also has openModal() function , which will add an active-modal class to #modal-wrappper and it will make the modal open on the screen.
The closeModal() function will remove the class from #modal-wrapper div. And the modal will disappear.
You can disable the scrolling behavior on a mobile device where we don’t use a mouse wheel to scroll up and down a page, by following the instructions here: Disable Scroll in Mobile Device