Can't get scripts to work on my pages

[WikiJS-pixel]

Good day!

What is needed for at least a very simple script to work?
I disabled the Sanitize HTML.
I tried several options in Page Properties => Scripts:

<script type="text/javascript">
function myFunction() { 
  alert("Hello! I am an alert box!"); 
}
</script>

HTML:
<button onclick="myFunction()">Try it</button>

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script> 

HTML:
<p id="demo"></p>

To no avail.