This tiny plugin is designed to show the progress of the page scrolling interactively. There are two types of actions: onScrolled and onChanged. They can be used together or separately.

• onScrolled - returns to the progress for each scroll event. It is convenient to use when you need to display progress in real time.
• onChanged - works only when one paragraph is replaced to another. This is useful for switching the active menu item in the navigation block.

LiveDemo

All you need is a navigation menu with links to the relevant paragraphs in the text. When initializing an object, you need to specify cursor and menu selectors, as well as a callback function.

When the onScrolled event is used, an object will be sent to the processing unit:

    Progress {
        // id of current paragraph
        Id: string;
        // % of paragraph being reviewed
        Percent: number;
    }

When the onChanged event is used, the id of the current paragraph will be sent to the processing unit.

When the window is changed in size, the script automatically will be adjuscted to the proportional value. This is sometimes needed in the mobile version. When the device screen is rotated, the scrolling will continue to work correctly.

npm i dual-side-scroll

Take the minified version of the script from dist and place it in your application directory. Make sure the plugin connection string is located above the connection string of your scripts.

<script src="./<your_js_directory>/scroll-progress.min.js"></script>

For debugging purposes, there is an unminified version with sourcemap.

The source code of the page LiveDemo script.

document.addEventListener("DOMContentLoaded", function (event) {
    let currentParagraphName = document.getElementById('current-paragraph-name');
    let currentParagraphPercent = document.getElementById('current-paragraph-percent');

    new ScrollProgress.Init(
        "#cursor",
        "menu",
        progress => {
            currentParagraphName.innerText = document.getElementById(progress.Id).innerText;
            currentParagraphPercent.innerText = progress.Percent + '%';
        },
        id => {
            document.querySelectorAll('a[href*="link"]')
                .forEach(element => 
                    element.classList.remove('active-meny-item')
                );
            document.querySelector(`[href="#${id}"]`).classList
                .add('active-meny-item');
        }
    );
});

• Interactive cursor to scroll the page
• Bookmarks in paragraphs