4 ms·

I've always been fascinated by this, but I have never known what it would be useful for. Does anyone know of any practical use cases?

by petcat 8mo ago

varun_ch 8mo ago
Maybe if you’ve got some ancient software that’s missing source code and only runs with X Y and Z conditions, you could continue to offer it on the web and build around it like that? Not sure if that would be practical at all, but could be interesting
maxloh 8mo ago
My college professor used it to teach us the Linux command line We have Windows PCs in the classroom.
- jgtrosh 8mo ago
  Similarly I've used it for technical interviews.
omoikane 8mo ago
I use bellard.org/jslinux to test compilation of strange code sometimes[1], since it came with compilers that are different versions from what I have installed locally, and it's easier to open up a browser than starting a VM. [1] For example: https://www.ioccc.org/2020/yang/index.html#:~:text=tcc%200.9.25%20on-,JSLinux,-Output%20of%20Mile https://www.ioccc.org/2020/yang/index.html#:~:text=tcc%200.9... https://www.ioccc.org/2018/yang/index.html#:~:text=tcc%200.9.25%20on-,JS/Linux,-Nuko%20compiles%20without https://www.ioccc.org/2018/yang/index.html#:~:text=tcc%200.9...
s-macke 8mo ago
Most such emulators have Internet access on the IP level. Therefore, this is a very cheap way to test anything on the Internet. apk add nmap nmap your.domain.com However, the speed is heavily throttled. You can even use ssh and login to your own server. It can also be used as a very cheap way to provide a complete build environment on a single website, for example to teach C/C++. Or to learn the shell. You don't have to install anything.
- Onavo 8mo ago
  You need backend proxies, the browser doesn't allow ignoring CORS by default.
  - s-macke 8mo ago
    Exactly. And JSLinux is using one.
toast0 8mo ago
I use a similar emulator (v86) as a way to share my hobby OS. Approximately zero people, even my friends, are going to boot my hobby OS on real hardware; I did manage to convince some of them to run it in qemu, but it's difficult. A browser environment shows the thing quite well; and easy networking is cool too. My hobby OS itself is not very useful, but it's fun if you're in the right mood.
redleader55 8mo ago
Agentic workloads create and then run code. You don't want to just run that code in a "normal" environment like a container, or even a very well protected VM. There are other options, ofc - eg. gvisor, crossvm, firecracker, etc, but this one is uncommon enough to have a small number of attackers trying to hack it.
- srdjanr 8mo ago
  What's wrong with a well protected VM? Especially compared to something where the security selling point is "no one uses it" (according to your argument; I don't know how secure this actually is)
  - g947o 8mo ago
    Nothing, but "there are already working options" does not necessarily mean we shouldn't try new (and sometimes weird) things
    - TacticalCoder 8mo ago
      Yeah but GP was answering to a comment saying "you don't want to run code in a well protected VM". Which is of course complete non sense to say and GP was right to question it.
    - cloudfudge 8mo ago
      GP says "You don't want to just run that code in ... even a very well protected VM." Why?
      - redleader55 8mo ago
        Because unless you can fund several teams - kernel, firmware(bios,etc), GPU drivers, qemu, KVM, extra hardening(eg. qemu runs under something like bpfilter) + a red team, security through obscurity is cheaper. The attack surface area is just too large.
postalrat 8mo ago
Some sort of web based archive of applications/etc where you can boot them up in your browser.
- peterburkimsher 8mo ago
  That’s what I’d like to use it for as well, but it’s difficult to do so because there’s no way to edit the disk image. Any advice on how to create a JSLinux clone with a specific file pre-installed and auto-launching would be much appreciated!
  - progrium 8mo ago
    Working with VMs always felt difficult because of this. So authoring was built-in to Docker. Now you can use Apptron to author and embed a Linux system on a web page. This aspect is usable, but it's only going to get better.
  - vexnull 8mo ago
    [flagged]
shirro 8mo ago
We are a playful species. People enjoy play. If we didn't have to work for a living but still enjoyed food security that is all most of us would do. But we are also a very exploitative species, some more than others. Companies have made billions of dollars on top of Fabrice Bellard's works, qemu, ffmpeg etc. These companies don't have any imagination. Their management has no vision. They could not create anything new and wonderful if they tried. People like Fabrice do and we are all richer for it. If your asking about the practical use you are likely in the exploitative mindset which is understandable on HN. The hacker/geek mindset enjoys this for what it is.
kristianp 8mo ago
https://infinitemac.org/ https://infinitemac.org/ is an example of a good use: users can try out old versions of Mac OS, to see what's changed and what software used to be available for old versions. It doesn't use JSLinux, but other emulators [1] [1] https://blog.persistent.info/2025/03/infinite-mac-os-x.html https://blog.persistent.info/2025/03/infinite-mac-os-x.html
Towaway69 8mo ago
I guess for the author its learning about how Linux can be ported to the browser. For us, it's more of a nice amusement. But then again, I've never understood why Buddhist monks create sand mandalas[1] and then let them be blown away (the mandalas not the monks!). I think one should see it from the authors PoV instead of thinking "what is in it for me". If I were to use this, then to create digital sand mandalas in the browser! ;) [1]: https://en.wikipedia.org/wiki/Sand_mandala https://en.wikipedia.org/wiki/Sand_mandala

I've always been fascinated by this, but I have never known what it would be useful for. Does anyone know of any practical use cases?

by petcat 8mo ago

I've always been fascinated by this, but I have never known what it would be useful for. Does anyone know of any practical use cases?

varun_ch 8mo ago

Maybe if you’ve got some ancient software that’s missing source code and only runs with X Y and Z conditions, you could continue to offer it on the web and build around it like that? Not sure if that would be practical at all, but could be interesting

maxloh 8mo ago

My college professor used it to teach us the Linux command line We have Windows PCs in the classroom.

jgtrosh 8mo ago
Similarly I've used it for technical interviews.

omoikane 8mo ago

I use bellard.org/jslinux to test compilation of strange code sometimes[1], since it came with compilers that are different versions from what I have installed locally, and it's easier to open up a browser than starting a VM. [1] For example: https://www.ioccc.org/2020/yang/index.html#:~:text=tcc%200.9.25%20on-,JSLinux,-Output%20of%20Mile https://www.ioccc.org/2020/yang/index.html#:~:text=tcc%200.9... https://www.ioccc.org/2018/yang/index.html#:~:text=tcc%200.9.25%20on-,JS/Linux,-Nuko%20compiles%20without https://www.ioccc.org/2018/yang/index.html#:~:text=tcc%200.9...

s-macke 8mo ago

Most such emulators have Internet access on the IP level. Therefore, this is a very cheap way to test anything on the Internet. apk add nmap nmap your.domain.com However, the speed is heavily throttled. You can even use ssh and login to your own server. It can also be used as a very cheap way to provide a complete build environment on a single website, for example to teach C/C++. Or to learn the shell. You don't have to install anything.

Onavo 8mo ago
You need backend proxies, the browser doesn't allow ignoring CORS by default.
- s-macke 8mo ago
  Exactly. And JSLinux is using one.

toast0 8mo ago

I use a similar emulator (v86) as a way to share my hobby OS. Approximately zero people, even my friends, are going to boot my hobby OS on real hardware; I did manage to convince some of them to run it in qemu, but it's difficult. A browser environment shows the thing quite well; and easy networking is cool too. My hobby OS itself is not very useful, but it's fun if you're in the right mood.

redleader55 8mo ago

Agentic workloads create and then run code. You don't want to just run that code in a "normal" environment like a container, or even a very well protected VM. There are other options, ofc - eg. gvisor, crossvm, firecracker, etc, but this one is uncommon enough to have a small number of attackers trying to hack it.

srdjanr 8mo ago
What's wrong with a well protected VM? Especially compared to something where the security selling point is "no one uses it" (according to your argument; I don't know how secure this actually is)
- g947o 8mo ago
  Nothing, but "there are already working options" does not necessarily mean we shouldn't try new (and sometimes weird) things
  - TacticalCoder 8mo ago
    Yeah but GP was answering to a comment saying "you don't want to run code in a well protected VM". Which is of course complete non sense to say and GP was right to question it.
  - cloudfudge 8mo ago
    GP says "You don't want to just run that code in ... even a very well protected VM." Why?
    - redleader55 8mo ago
      Because unless you can fund several teams - kernel, firmware(bios,etc), GPU drivers, qemu, KVM, extra hardening(eg. qemu runs under something like bpfilter) + a red team, security through obscurity is cheaper. The attack surface area is just too large.

postalrat 8mo ago

Some sort of web based archive of applications/etc where you can boot them up in your browser.

peterburkimsher 8mo ago
That’s what I’d like to use it for as well, but it’s difficult to do so because there’s no way to edit the disk image. Any advice on how to create a JSLinux clone with a specific file pre-installed and auto-launching would be much appreciated!
- progrium 8mo ago
  Working with VMs always felt difficult because of this. So authoring was built-in to Docker. Now you can use Apptron to author and embed a Linux system on a web page. This aspect is usable, but it's only going to get better.
- vexnull 8mo ago
  [flagged]

shirro 8mo ago

We are a playful species. People enjoy play. If we didn't have to work for a living but still enjoyed food security that is all most of us would do. But we are also a very exploitative species, some more than others. Companies have made billions of dollars on top of Fabrice Bellard's works, qemu, ffmpeg etc. These companies don't have any imagination. Their management has no vision. They could not create anything new and wonderful if they tried. People like Fabrice do and we are all richer for it. If your asking about the practical use you are likely in the exploitative mindset which is understandable on HN. The hacker/geek mindset enjoys this for what it is.

kristianp 8mo ago

https://infinitemac.org/ https://infinitemac.org/ is an example of a good use: users can try out old versions of Mac OS, to see what's changed and what software used to be available for old versions. It doesn't use JSLinux, but other emulators [1] [1] https://blog.persistent.info/2025/03/infinite-mac-os-x.html https://blog.persistent.info/2025/03/infinite-mac-os-x.html

Towaway69 8mo ago

I guess for the author its learning about how Linux can be ported to the browser. For us, it's more of a nice amusement. But then again, I've never understood why Buddhist monks create sand mandalas[1] and then let them be blown away (the mandalas not the monks!). I think one should see it from the authors PoV instead of thinking "what is in it for me". If I were to use this, then to create digital sand mandalas in the browser! ;) [1]: https://en.wikipedia.org/wiki/Sand_mandala https://en.wikipedia.org/wiki/Sand_mandala