js add class and remove class code example

Example 1: es6 add and remove class

let el = document.getElementById('container');

//remove class
el.classList.remove('first');

//remove class
el.classList.add('first');

Example 2: add to classlist javascript

Add multiple classes to a <div> element:
document.getElementById("myDIV").classList.add("mystyle", "anotherClass", "thirdClass");

Remove a class from a <div> element:
document.getElementById("myDIV").classList.remove("mystyle");

Remove multiple classes from a <div> element:
document.getElementById("myDIV").classList.remove("mystyle", "anotherClass", "thirdClass");

Toggle between two classes for a <div> element:
document.getElementById("myDIV").classList.toggle("newClassName");

Find out if an element has a "mystyle" class:
document.getElementById("myDIV").classList.contains("mystyle");

Example 3: js remove class

const removeClass = (element, name) => {
    const pattern = new RegExp('(?:^|\\s)'+ name + '(?:\\s|$)', 'g');
    element.className = element.className.replace(pattern, "");
};