CODE t!ps

Add or Remove HTML classes in Jquery

Adding new HTML class is a no-brainer

You can do this with jQuery. This example function below will add and remove my-new-class to the <div>.
// ## add class
$(‘div’).addClass(‘my-new-class’);

// ## remove class
$(‘div’).removeClass(‘my-new-class’);
We can also use standard JavaScript code to add/remove HTML classes like so:
// add class
document.getElementById(‘elem’).className = ‘my-new-class’;

// remove class
document.getElementById(‘elem’).className = document.getElementByTag(‘div’).className.replace( /(?:^|\s)my-new-class(?!\S)/g , ” )
The code as you can see above is less straightforward than when we are doing it with a JavaScript Framework jQuery. But if you don’t want to rely on a framework, you can always use a new JavaScript API called classList.

Recommended Reading: Obtaining User Location With HTML5 Geolocation API

Using ClassList API
Similar to jQuery, classList provides a set of methods that allow us to modify HTML classes.

In a case where there is a div with multiple classes, we can retrieve the classes that are assigned in the div using classList.
var classes = document.getElementByID(‘elem’).classList;
console.log(classes);
When we open the browser Console, we can see the list of the classes.

To add and remove class, we can use .add() and .remove().
var elem = document.getElementByID(‘elem’);

// add class
elem.classList.add(‘my-new-class’);

// remove class
elem.classList.remove(‘my-new-class’);
Adding multiple classes can also be done by separating each class with a comma:
elem.classList.add(‘my-new-class’, ‘my-other-class’);
To check whether certain elements contain the specified class, we can use .contains(). It will return true if the class specified is present, and return false if it does not.
elem.classList.contains(‘class-name’);
We can also toggle the class using .toggle(). The following code snippet shows how we bind the .toggle()method with a mouse click event.
var button = document.getElementById(‘button’);
function toggle() {
elem.classList.toggle(‘bg’);
}
button.addEventListener(‘click’, toggle, false);
Check out the demo in action from the following links.