JSFiddle - React, Tailwind, and code Playground

HTML

<form action="">
    <input type="text" id="nome" />
    <input type="text" id="email" />
    <input type="text" id="telefone" />
    <input type="submit" value="enviar" />
</form>

JavaScript

$(document).ready(function (){
    validate();
    $('#nome, #email, #telefone').change(validate);
});

function validate(){
    if ($('#nome').val().length   >   0   &&
        $('#email').val().length  >   0   &&
        $('#telefone').val().length    >   0) {
        $("input[type=submit]").prop("disabled", false);
    }
    else {
        $("input[type=submit]").prop("disabled", true);
    }
}