FWIW My solution to finding and debugging CONTENT scripts.
- FireFox Developers Edition
- This Firefox, load extension etc
- include a line "console.log(some variable/text) " in the script
- open debugger , select console, select logs
- run target website (hence script)
- click on the reference to your script file against logs (or error msg) on RHS
- observe script displayed, set breakpoints etc etc.
Having followed many suggestions above and perused developer.mozilla.org the conclusion has to be that FireFox Portable (at least) cannot be used to debug CONTENT scripts. They run - if good code. & clicking (as per 6) above) displays code but not a debugger version, thankfully at the line involved in the error/log. Which I found normal when debugging JavaScript generally on my websites, but there the scripts are accessible anyway.
Oh & until the code is finished, the inevitable line:
‘document.body.style.border = “5px solid red”;’
is left at the end as a security blanket.