MediaWiki:Common.js

/* Any JavaScript here will be loaded for all users on every page load. */
console.log(document.getElementsByClassName("mw-logo-container").innerHTML());

var spanContainer = document.getElementsByClassName("mw-logo-container");

console.log(spanContainer.innerHTML());

var aTag = document.createElement('a');

aTag.innerHTML = 'I am a link';

aTag.setAttribute('href', 'http://www.nu.nl');

spanContainer.appendChild(aTag);