There is some code I wanted to put into JSFiddle. It didn’t work. Narrowing it
down I can’t even get this simplest of code to work:

JSFiddle

function displaymessage() {
  alert("Hello World!");
}



<form>
  <input type="button" value="Click me!" onclick="displaymessage()" />
</form>

<p>By pressing the button above, a function will be called. The function will alert a message.</p>

The alert box doesn’t show up in the JSFiddle.