JSFiddle - React, Tailwind, and code Playground

HTML

<select id="1d" name="camp">
    <option data-url="week_1" value="Week 1">30th July</option>
    <option data-url="week_2" value="Week 2">6th August</option>
</select>
<input type="hidden" name="camp_url" id="1e">

JavaScript

$("#1d").on("change", function () {
    var url = $(this).children(":selected").data("url");
    $("#1e").val(url);
    alert(url);
});