Comment by jasonlaster11 | Hacker News Reader

Comment by jasonlaster11 | Hacker News Reader

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We're making progress on an experimental version in Firefox DevTools. It's not on the roadmap, but it is easy to try and we'd love feedback.

https://developer.mozilla.org/en-US/docs/Mozilla/Projects/We...

This video highlights some of the existing functionality:

https://www.youtube.com/watch?v=yS5ai04TP5Y&t=4s

1. a realtime recording button 2. a timeline view of events on the top 3. the ability to scan back to a console message 4. the ability to rewind to a breakpoint 5. the ability to add a logPoint in the debugger and see the messages in the console quickly

I'll second other comments on the complexity side. Our architecture works on the Operating System level, which makes it fast and non-invasive, but the difficulty level in terms of pulling something like this off is very high as you have to understand the browser architecture from the system calls it makes, to way processes behave, to graphics, the JS engine, and DevTools architecture.

I think we're in a good place in terms of getting feedback and iterating on the product. There's lot's to do and it is very exciting!

Wow this looks amazing already. I think something as simple as recording the input and output of a single function would be my most common use case and would make a world of difference for me but this goes way above and beyond.

Would it reduce the graphics, OS, etc complexity to just have the basic single function IO recording?

The problems I see with limiting the scope to single function IO are

1. JS is dynamic and a single function can do a lot, even if you try to stub out the world.

2. from a product perspective it would be hard to communicate what is going on.

3. Perhaps console logs could cover a lot of these cases.

Does that make sense? What are you thinking of?

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We definitely want to make it easy to visualize function calls (inputs/outputs). For instance,

- see outlier function arguments (the time the first param was null) or the function returned early...

- see outlier call sites (the time when the function was called from a different call site)

- see outlier timings (the time when the function called when some other state was null or a promise was pending) i.e. race detection

On the other side, we would love to help users see the impact of a function call. For instance,

- program slicing: the other code that was run because this function was invoked

- data tainting: the data that was either read or written to because this function was invoked

> I'll second other comments on the complexity side.

Ditto for Chrome DevTools. If I recall correctly, it’s feasible but would be a huge undertaking. Demand for the feature would have to be very large to justify the work involved.

Very exciting project and thrilled to see something of this complexity come out of the JS world! Great work guys

Any plans bringing this to Windows? It appears this is currently only available on macOS.

We'd love to.

We have a WIP patch. At the moment, we're prioritizing MVP functionality, performance, and stability.

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