I am just starting to explore Scratchx Experimental Extensions. Using the latest Raspberry Pi with Stretch OS and Scratch 2 I have the demo file waitblock.js in my ‘home’ directory and can load it by entering /home/pi/waitblock.js in the URL: dialog box.

On my mac with High Sierra OS using scratchx and waitblock.js in /Users/alan/ I am unable to load the file no matter what I enter in the dialog box e.g
waitblock.js
alan/waitblock.js
Users/alan/waitblock.js
Macintosh\ HD/alan/waitblock.js
Macintosh HD/alan/waitblock.js

Does anyone have a solution?

Open this file in a program like Notepad++, and select “Run”, choose your browser, and copy the URL. This should be the file location that you can use.