JSFiddle - React, Tailwind, and code Playground
HTML
<form name="formulario">
<input type="text" name="nome" />
<input type="button" name="submit" value="checar" />
</form>
<div id="resultado"></div>
JavaScript
document.formulario.submit.onclick=function() {
var nome = this.parentNode.nome.value;
var isSmith = (nome.toLowerCase().search(/smith/) > -1);
document.getElementById('resultado').innerHTML += "Checando: "+nome+"<br />Smith encontrado? "+isSmith+"<br /><hr /><br />";
}