How Can I Trigger CSS3 Animations Only When Elements Scroll into View?

Trigger CSS3 Animations on Scrolling into View

Objective: Activate CSS3 animations on elements when they're scrolled into the user's view.

Problem: Due to overwhelming content pushing an animated bar chart off-screen, its animations begin prematurely when the page loads.

Solution: Utilize JavaScript or jQuery to monitor scrolling events.

Implementation:

1. Capture Scroll Events: Use JavaScript or jQuery to capture scroll events, ensuring that the animation triggers only when the target element is within the viewport.
2. Check Element Visibility: Inside the scroll event listener, a function like isElementInViewport() determines if the animated element has entered the user's view.
3. Start Animation: Once the element is visible, add a class (e.g., "start") to trigger the animation.

Example:

In this example, jQuery is used to handle scroll events and identify when the bar chart becomes visible:

$(window).scroll(function() {
    var $elem = $('.bar .level');

    if (!$elem.hasClass('start') && isElementInViewport($elem)) {
        $elem.addClass('start');
    }
});

This JavaScript code ensures that the bar chart's animation begins only when the user scrolls down and the chart becomes visible within the viewport.

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