classList
is pretty smart and the most modern system of manipulating CSS class names in elements via JavaScript.
Adding class name:
const element = document.getElementById('txtMyText'); element.classList.add('myClass');
Removing class name:
const element = document.getElementById('txtMyText'); element.classList.remove('myClass');
Removing multiple class names:
const element = document.getElementById('txtMyText'); element.classList.remove('myClass1', 'myClass2')
Thanks to clubmate.fi