How synchronize the scroll of two divs with JavaScript

by Silvia Mazzetta Date: 26-05-2023 javascript

In case you have two divs of different sizes you may sometimes want to scroll both at the same time but at different speeds depending on their size. For example, you could have text in one and images in the other and want to scroll both at the same time. To achieve this, we will do it with the jQuery JavaScript library.

And no....jQuery is not dead.

To synchronize the scroll positions we can use .scrollTop() to know the position of the content with respect to the top of the page.

First, we place the page div with the main content and then the block div with the secondary content that will scroll with respect to the main one according to its position. This second div will have to have a fixed position with respect to the page. That is to say, that in its CSS it will have to contain the artribute "position: fixed".

 
<div id="mypage">
  <p class="mypageHeader">my page header</p>
  <p>Here we place our text</p>
  .........
  <p>more text...</p>
  <p> class="footerPage">footer page</p>
</div>

<div id="box">
  <div id="boxHeight">
    <p class="boxheader">box header</p>
    <p>Here we place our text</p>
    .........
    <p>more text</p>
    <p class="boxfooter">footer box</p>
  </div>
</div>
 

Let's go now with the JavaScript code. In pageH we get the difference between the height of the page div and the height of the window to calculate the height of the non-visible content. In pagT we get the scroll position of the window minus the height that we have already advanced in the page div.

Finally we move the block div correspondingly with respect to the page div so that they move the same proportional distance based on their height.

 
$(window).scroll(function() {      
  var pagH = $('#mypage').height() - $(this).height();      
  var pagT = this.scrollY - $('#mypage').offset().top;      
  $('#box').scrollTop(pagT / pagH * ($('#boxHeight').height() - $(this).height()));  
});
 

The styles of the divs are as follows:

 
body {    
position: relative;    
margin: 0 auto;  
}    
#mypage {    
position:relative;    
width: 550px;  
}    
#mypage p {    
text-align: justify;  
}    
#box {    
background: #027EBA;    
display: block;    
width: 200px;    
height: 100%;    
position: fixed;    
right: 20px;    
top:0;    
overflow: hidden;  
}    
.mypageHeader, .footerPage {    
display: block;    
width: 100%;    
margin: 0 auto;    
background: red;    
color: white;    
font-weight: bold;    
font-size: 16px;  
}    
.boxheader, .boxfooter {    
display: block;    
width: 100%;    
margin: 0 auto;    
background: green;    
color: white;    
font-weight: bold;    
font-size: 16px;  
}
 

IMPORTANT: don't forget to add jQuery.

 
by Silvia Mazzetta Date: 26-05-2023 javascript hits : 12471  
 
Silvia Mazzetta

Silvia Mazzetta

Web Developer, Blogger, Creative Thinker, Social media enthusiast, Italian expat in Spain, mom of little 9 years old geek, founder of  @manoweb. A strong conceptual and creative thinker who has a keen interest in all things relate to the Internet. A technically savvy web developer, who has multiple  years of website design expertise behind her.  She turns conceptual ideas into highly creative visual digital products. 

 
 
 

Related Posts

How to upload files to the server using JavaScript

In this tutorial we are going to see how you can upload files to a server using Node.js using JavaScript, which is very common. For example, you might want to…

How to combine multiple objects in JavaScript

In JavaScript you can merge multiple objects in a variety of ways. The most commonly used methods are the spread operator ... and the Object.assign() function.   How to copy objects with…

The Payment Request API: Revolutionizing Online Payments (Part 2)

In the first part of this series, we explored the fundamentals of the Payment Request API and how it simplifies the payment experience. Now, let's delve deeper into advanced features…

The Payment Request API: Revolutionizing Online Payments (Part 1)

The Payment Request API has emerged as the new standard for online payments, transforming the way transactions are conducted on the internet. In this two-part series, we will delve into…

Let's create a Color Picker from scratch with HTML5 Canvas, Javascript and CSS3

HTML5 Canvas is a technology that allows developers to generate real-time graphics and animations using JavaScript. It provides a blank canvas on which graphical elements, such as lines, shapes, images…

How do you stop JavaScript execution for a while: sleep()

A sleep()function is a function that allows you to stop the execution of code for a certain amount of time. Using a function similar to this can be interesting for…

Mastering array sorting in JavaScript: a guide to the sort() function

In this article, I will explain the usage and potential of the sort() function in JavaScript.   What does the sort() function do?   The sort() function allows you to sort the elements of…

Infinite scrolling with native JavaScript using the Fetch API

I have long wanted to talk about how infinite scroll functionality can be implemented in a list of items that might be on any Web page. Infinite scroll is a technique…

Sorting elements with SortableJS and storing them in localStorage

SortableJS is a JavaScript extension that you will be able to use in your developments to offer your users the possibility to drag and drop elements in order to change…

What is a JWT token and how does it work?

JWT tokens are a standard used to create application access tokens, enabling user authentication in web applications. Specifically, it follows the RFC 7519 standard. What is a JWT token A JWT token…

Template Literals in JavaScript

Template literals, also known as template literals, appeared in JavaScript in its ES6 version, providing a new method of declaring strings using inverted quotes, offering several new and improved possibilities. About…

How to use the endsWith method in JavaScript

In this short tutorial, we are going to see what the endsWith method, introduced in JavaScript ES6, is and how it is used with strings in JavaScript. The endsWith method is…

Clicky