js change css class code example

Example 1: change elements class javascript

document.getElementById("MyElement").classList.add('MyClass');

document.getElementById("MyElement").classList.remove('MyClass');

if ( document.getElementById("MyElement").classList.contains('MyClass') )
{
document.getElementById("MyElement").classList.toggle('MyClass');
}

Example 2: dynamically change css class with javascript

document.getElementById('idOfElement').classList.add('newClassName');