Toggle CSS Class for Dynamic Styling

const element = document.getElementById('myElement');

// Add a class
element.classList.add('active');

// Remove a class
element.classList.remove('inactive');

// Toggle a class (adds if not present, removes if present)
element.classList.toggle('highlight');

// Check if a class exists
if (element.classList.contains('active')) {
  console.log('Element has the active class.');
}

How it works: This snippet demonstrates how to manipulate an element's CSS classes using the `classList` API. `add()` appends a class, `remove()` deletes one, and `toggle()` intelligently adds or removes a class based on its current presence. `contains()` allows checking for a class without complex string parsing. This is crucial for dynamic styling based on user interaction or application state.