safari – How to run a Shortcut from a web page in iOS

I am trying to use the Shortcuts feature of iOS.

I want to run some simple JavaScript on a web page.

I made a new Shortcut, added “Run JavaScript on Web Page”.

The contents of the JavaScript are

alert("hello world");
completion();

I named the shortcut “do hello world”.

Now how do I trigger this to run on a web page?

I’ve googled and it seems that I should be able to click on the “export” button in Safari and run the shortcut from the panel that appears, but I do not see my shortcut in that list.