JSFiddle - React, Tailwind, and code Playground

HTML

<table border=1 id="table1" class="table3">
<tr>
<td>Пример</td>
</tr>
</table>

SCSS

#table1 {
  display:block;
}
.table4 {
	-moz-box-shadow:0 0 10px #4195fc;
-webkit-box-shadow:0 0 10px #4195fc;
box-shadow:0 0 10px #4195fc;
}
.table3 {
	-moz-box-shadow:0 0 10px #ffd700;
-webkit-box-shadow:0 0 10px #ffd700;
box-shadow:0 0 10px #ffd700;
}

JavaScript

var elem = document.querySelector("#table1")
var a=0;
if (a==0) {
elem.classList.remove('table3');
elem.classList.add('table4');
}