------------------- <div id="bigdiv" style="position:fixed; top: 0px; left: 505px;"> <button id="btn" class="box">Random</button> <iframe id="frame" src="rss-scrolling-source01.html" frameborder="0" scrolling="no" height=65 width=400></iframe> </div> <script> var cat1 = [    "https://ry3yr.github.io/OSTR/Diarykeepers_Homepage/rss-scrolling-source01.html",    "https://ry3yr.github.io/OSTR/Diarykeepers_Homepage/rss-scrolling-source02.html" ]; var myFrame = document.getElementById("frame"); function getRandomUrl(myFrame) { var index = Math.floor(Math.random()*cat1.length); var url = cat1[index]; myFrame.src = url; } btn.addEventListener("click", function() { getRandomUrl(myFrame); }); </script> </plaintext>