JSFiddle - React, Tailwind, and code Playground

HTML

<select id="Alert_Me" name="Alert_Me" class="form-control">
    <option value="1" selected="selected">Immediately</option>
    <option value="2">Once a day</option>
    <option value="3">Save</option>
</select>
<div id="time-formgroup" style="display: none;">THIS DIV IS SHOWN</div>

JavaScript

$("#Alert_Me").on("change", function () {
    $("#time-formgroup").toggle($(this).val() == 2);
});