JSFiddle - React, Tailwind, and code Playground

by Sachin Sharma

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script> 

<input type="text" name="txtuname" id="txtuname" />
<span id="errmsg"></span>

JavaScript

$(document).ready(function(){
	$("#txtuname").keypress(function(e){ 
		var validExp = /^[0-9a-z]+$/gi;
		var val = $(this).val();
		if(val.match(validExp))
		{
			$("#errmsg").html("");
			return true;
		}
		else
		{
			$("#errmsg").html("Number and letters Only"); 
			return false;
		}
	});
});