See trigger:Script. The information there also appears in manual:Windows (just below the image) and manual:Macros (near the bottom). And “Or by script” is present in the trigger section of every macro. Yet I never noticed any of this until today.
This is a truly remarkable feature. It shows how to invoke the selected macro from any of seven languages and by URL, all ready to copy-and-paste. I wish I had known about this a very long time ago.