index.js
function mergeClassNames(from, to) {
    const classNames = from.classList;
    for (let i = 0; i < classNames.length; i++) {
        to.addClass(classNames[i]);
    }

    return to;
}
function mergeClassNames(from, to) {
    const classNames = from.classList;
    for (let i = 0; i < classNames.length; i++) {
        to.addClass(classNames[i]);
    }

    return to;
}
function mergeClassNames ( from , to ) { const classNames = from . classList ; for ( let i = 0 ; i < classNames . length ; i ++ ) { to . addClass ( classNames [ i ] ) ; } return to ; }
Adds class names from first node to second one
@param  {Node} from
@param  {Node} to
@return {Node}
Adds class names from first node to second one