Can you explain me , how this function works?

Question

function dragStart(){
this.className += ' hold';
setTimeout()) => (this.className = 'invisible'),0);
}

Full code:

https://code.sololearn.com/WHtv7XEBcM4g/?ref=app

Answer 1

well, the function changes the class to invisible, which I saw in the CSS changed the element to invisible. Also, the hold class gives the element a border.