JSFiddle - React, Tailwind, and code Playground

HTML

<input name="tesztinput1" type="text" />
<input name="tesztinput3" type="button" disabled="disabled" value="Click" />

JavaScript

$(document).ready(function () {
    $('input[name="tesztinput1"]').keyup(function () {
        alert('Content has been changed');
        if ($(this).val()) {
            $('input[name="tesztinput3"]').prop('disabled', false);
        }
    })
});