How to identify which element scroll is being used using JavaScript ?

Last Updated : 31 Jul, 2024

To identify which element is being scrolled using JavaScript, you can attach scroll event listeners to specific elements. This allows you to determine which element's scroll event is active, enabling tailored responses or interactions based on the particular element being scrolled.

Using Scroll event listener

This approach involves adding scroll event listeners to two scrollable elements. When either element is scrolled, the event listener updates the text content of a designated result area to indicate which element is being scrolled. This allows for real-time feedback on user interactions with the scrollable elements.

Example: In this example, we've created two scrollable elements and added the 'scroll' event listener to both of them. As soon as any of the elements are scrolled, the scroll event of that particular element is fired.

HTML

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" 
          content="width=device-width, 
                   initial-scale=1.0" />
    <title>How to identify which element
        scroll is being used using JavaScript?
    </title>

    <style>
        h1 {
            color: #2f8d46;
            font-weight: bold;
            margin: 40px;
        }

        #first {
            height: 200px;
            width: 400px;
            overflow-y: scroll;
            margin: 40px;
        }

        #second {
            margin: 40px;
            height: 200px;
            width: 400px;
            overflow-y: scroll;
        }

        #scrolled {
            margin: 40px;
        }
    </style>
</head>

<body>
    <h1>GeeksforGeeks</h1>

    <!--First element-->
    <div id="first">
        <h2>First element</h2>

        <p>
            JavaScript is a lightweight, cross-platform
            and interpreted scripting language. It is well-known
            for the development of web pages, many non-browser
            environments also use it. JavaScript can be used for
            Client-side developments as well as Server-side
            developments. JavaScript contains a standard library
            of objects, like Array, Date, and Math, and a core
            set of language elements like operators, control
            structures, and statements.
            History of JavaScript: It was created in 1995
            by Brendan Eich while he was an engineer at Netscape.
            It was originally going to be named LiveScript but
            was renamed. Unlike most programming languages,
            the JavaScript language has no concept of input
            or output. It is designed to run as a scripting
            language in a host environment, and it is up to
            the host environment to provide mechanisms for
            communicating with the outside world. The most
            common host environment is the browser.
        </p>

    </div>

    <!--Second element-->
    <div id="second">
        <h2>Second element</h2>

        <p>
            JavaScript is a lightweight, cross-platform
            and interpreted scripting language. It is well-known
            for the development of web pages, many non-browser
            environments also use it. JavaScript can be used for
            Client-side developments as well as Server-side
            developments. JavaScript contains a standard library
            of objects, like Array, Date, and Math, and a core
            set of language elements like operators, control
            structures, and statements.
            History of JavaScript: It was created in 1995
            by Brendan Eich while he was an engineer at Netscape.
            It was originally going to be named LiveScript but
            was renamed. Unlike most programming languages,
            the JavaScript language has no concept of input
            or output. It is designed to run as a scripting
            language in a host environment, and it is up to
            the host environment to provide mechanisms for
            communicating with the outside world. The most
            common host environment is the browser.
        </p>

    </div>

    <div id="scrolled">
        <h3>Element being scrolled: <span id="result"></span></h3>
    </div>

    <script>

        //Selecting required elements from the DOM
        const first = document
            .querySelector("#first");
        const second = document
            .querySelector("#second");
        const result = document
            .querySelector("#result");

        //Adding the scroll event listener
        first
            .addEventListener("scroll",
                () => (result.textContent = "First"));
        second
            .addEventListener("scroll",
                () => (result.textContent = "Second"));
    </script>
</body>

</html>