JAVASCRIPT

javascript get element by class name change style

const boxes = document.querySelectorAll('.box');

boxes.forEach(box => {
  box.style.backgroundColor = 'purple';
  box.style.width = '300px';
});

js update css class name

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');