remove existing class from dv and add to new element using javascript code example

Example 1: javascript remoev css class

//remove a css class from an element
document.getElementById("myElementID").classList.remove("class_name");

Example 2: js remove class

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