How Can I Trigger CSS Animations with Pure JavaScript?

Trigger CSS Animations in JavaScript

In web development, CSS animations provide visually dynamic effects to web pages. However, triggering these animations using JavaScript can be a common challenge. For those who prefer not to use jQuery, this guide offers a solution for triggering CSS animations purely through JavaScript.

One effective approach is to utilize class manipulation. By adding or removing classes to an HTML element, you can trigger specific CSS animations. In JavaScript, this can be achieved through the className property of the HTMLElement object.

To demonstrate, consider the following example:

function start() {
  document.getElementById('logo').classList.add('animate');
}

In this script, the start function is invoked when the logo element is clicked. It adds the 'animate' class to the element.

To target the CSS animation, create a corresponding CSS rule for the 'animate' class:

.animate {
  animation: my-animation 2s forwards;
}

In this CSS rule, the 'my-animation' animation will be applied to any element with the 'animate' class.

Another method is through the style property of the HTMLElement object. This allows direct manipulation of the element's inline styles. To trigger an animation using this approach:

document.getElementById('logo').style.animation = 'my-animation 2s forwards';

As before, define the 'my-animation' animation in your CSS to specify the animation behavior.

Finally, for complex animations involving scrolling, you can use the scroll event listener:

window.addEventListener('scroll', () => {
  if (window.scrollY >= 100) {
    document.getElementById('logo').classList.add('animate');
  }
});

In this example, the animation starts when the user scrolls down past 100 pixels. Note that this method requires you to specify the CSS animation with a keyframe rule that triggers on scroll position.

Utilizing these techniques, you can now trigger CSS animations dynamically using pure JavaScript, unlocking a wide range of possibilities for creating visually engaging web applications.

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