remove by class name javascript 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: js remove class

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