https://weather.metoffice.gov.uk/public/adhoc/strike-action-banner.js

1"use strict";
2(function () {
3    var mainTag = document.querySelector("header"),
4        messageHeader = "Strike Action",
5        bannerElement = document.createElement("section");
6
7    bannerElement.classList.add("beta-banner-component");
8    bannerElement.innerHTML = '<div class="beta-banner-content container row">' +
9        '<div class="col-xs-12 col-sm-2 beta-sign">' + messageHeader + '</div>' +
10        '<div class="col-xs-12 col-sm-10 row beta-message">' +
11            '<div class="beta-banner-header col-xs-12 col-lg-12"><a href="https://www.metoffice.gov.uk/about-us/strikeaction">Industrial Action by members of Prospect Trade Union – Wed 10 May</a>. Services from the Met Office may be affected.</div>' +
12        '</div></div>';
13
14    if (typeof mainTag !== "undefined") {
15        mainTag.parentNode.insertBefore(bannerElement, mainTag.nextSibling);
16    }
17})();