How do you toggle a CSS class on a DOM element in JavaScript?
Aug 04, 2025 am 11:36 AM
The easiest way to switch the CSS class of DOM elements using JavaScript is to use the classList.toggle() method, which will automatically add or remove the specified class name; for example: element.classList.toggle('your-class-name'); if you need to force switching according to the conditions, you can pass in the second boolean parameter: true means adding class, false means removing class, such as element.classList.toggle('active', true); for old browsers (such as IE9 and below), className string operation can be used as a downgrade solution, and class names are manually added and decremented through split, indexOf and splice; but in modern development, it is recommended to use classList.toggle() directly because it is concise, readable and widely supported.
You can toggle a CSS class on a DOM element in JavaScript using the classList.toggle() method. It's simple, built into modern browsers, and doesn't require any libraries.
Use classList.toggle()
The easiest and most common way is:
element.classList.toggle('your-class-name');
This adds the class if it's not already present, and removes it if it is.
Example:
const button = document.getElementById('myButton');
button.addEventListener('click', function() {
this.classList.toggle('active');
}); In this example, clicking the button will add the active class the first time, remove it on the second click, and keep toggling with each click.
What if you need to conditionally toggle?
You can also pass a second parameter — a boolean — to force add or remove:
element.classList.toggle('active', true); // Forces add element.classList.toggle('active', false); // Forces remove
This is useful when you want to sync the class with a condition:
const isLoggedIn = true; userElement.classList.toggle('logged-in', isLoggedIn);
Fallback for older browsers?
If you're supporting very old browsers (like IE9 or below), classList may not be fully supported. In that case, you can use a polyfill or fall back to manipulating the className string manually:
function toggleClass(element, className) {
const classes = element.className.split(' ');
const index = classes.indexOf(className);
if (index === -1) {
classes.push(className);
} else {
classes.splice(index, 1);
}
element.className = classes.join(' ');
} But for most modern development, classList.toggle() is the standard and recommended approach.
Basically, just use element.classList.toggle('classname') — it's clean, readable, and widely supported.
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