JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.3/jquery.min.js"></script>
<span id="usernameStatus" data-valid="0">x</span>

JavaScript

function validUsername(data) {       
	if (data === 'true') {
		$("#usernameStatus").html("y").attr("data-valid", 1);
	} else {
		$("#usernameStatus").html("x").attr("data-valid", 0);
	}
}
$(function(){
	validUsername('true');  
});