var nameClass=document.getElementsByClassName("clase1");console.log("after", nameClass[0]);$(".clase1").removeClass();var nameClass=document.getElementsByClassName("clase1");console.log("before", nameClass[0]);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script><div class="clase1">I am a Div with class="clase1"</div>
// remove all class of all itemsconst items = [...document.querySelectorAll('.item')];for (const item of items) {item.classList.value = '';}
// remove all class of the first itemconst items = [...document.querySelectorAll('.item')];for (const [i, item] of items.entries()) {if(i === 0) {item.classList.value = '';}}