Nowadays many applications, and especially most big-name business application suites (G Suite, Microsoft Office online, etc), are converting all their web applications to Progressive Web Apps, adding Service Workers and such so that they work just fine when you're offline and sync to backup document changes and such whenever you reconnect later. Give it a couple years and it won't be a problem anymore.
The walled garden I speak of is the implementation of add-ons cryptographically signed by Mozilla only. Unless you run one of the betas (w/bugs) you cannot use any add-on not approved by Mozilla. And lately they've even been removing/banning add-ons that aren't illegal but otherwise upset outside corporations (ie, the paywall bypasser that uses googlebot's http headers substituted in).
It's important not to lump together the proprietary browsers (where the limit you speak of can only be worked around if the proprietors allow) and free software browsers which respect your software freedom, like Firefox.
You could modify Firefox source code to let you run whatever add-on you wish. With Firefox whatever changes you want are limited only by your willingness to implement them (either by doing the work yourself or working with others to get those changes made).
You can even distribute the improved Firefox variant browser to others and help the community. Hacker News recently had a story about some hackers doing exactly this with a variant they call Librefox. Other examples of Firefox variants include IceCat and the Tor Browser.
Is there a browser you would recommend, if we ignored their HTML/CSS rendering for a second, based on ethical considerations, so to speak? I like making things compatible when I don't need anything modern, and would be interested in hearing about any browsers you think are worth supporting.
In that sort of case I like to use explicit type casting, e.g.
if (Number(myNum) === 2) {}
For me this also extends to using `Boolean(val)` instead of `!!val`, etc.; though I understand the appeal of those nifty one-liners, I think they cause confusion in many places and don't communicate intent nearly as well.
Assuming you can include JS in the file, I imagine it would only run if the file was being parsed as HTML at the moment, not when parsed as a JPEG. That's the main point here: this file can be interpreted in two ways, but the data in it is treated very differently and has different effects depending on the way it's currently interpreted.
This won't answer the question directly, but these sorts of discussions always bring to my mind the famous quote from Jeremy Bentham: "The question is not, Can they reason?, nor Can they talk? but, Can they suffer?"
I mean, if you think about it, any time you run any installer, whether via brew install, apt-get install, or an .exe or .msi, you're effectively running someone else's unknown code on your system, often as a superuser (e.g. with sudo apt-get install). Is there a significant difference here? At least in this case you could potentially download the shell file and read it before you run it, unlike with a binary executable.
