JSFiddle - React, Tailwind, and code Playground

HTML

<form action="">
    <select name="gender">
        <option value="m">male</option>
        <option value="f">female</option>
    </select>
    <input type="hidden" name="user_id" value="1">
    <input type="submit" id="save1" value="Save">
</form>

<form action="">
    <select name="gender">
        <option value="m">male</option>
        <option value="f">female</option>
    </select>
    <input type="hidden" name="user_id" value="2">
    <input type="submit" id="save2" value="Save" hidden>
</form>

JavaScript

$(this).parent().children('input[type=submit]').hide();

$("select").on("change", function() {
    $(this).parent().children('input[type=submit]').show();
});