Add support for `--watch`

[Electroid]

What is the problem this feature will solve?

Node.js added support for node --watch in v18. --watch is common among other developer tools, so we should support it as well.

This is different than --hot, because --watch reloads the process, while --hot does not.

What is the feature you are proposing to solve the problem?

See https://github.com/oven-sh/bun/issues/1356#issuecomment-1284594045

What alternatives have you considered?

No response

[Jarred-Sumner]

It's not exactly the same thing

• --hot means "reload the code without restarting the process"
• --watch means "restart the process on change"

This sounds like a distinction without a difference but it impacts how people expect it to work.

I think Bun should potentially support both hot reloading and live reload, especially for tests. HMR for tests don't make much sense - you want a clean state before each run.

[Jarred-Sumner]

I think another option is to say "Did you mean --hot"? When they try "--reload" and it doesn't do anything

[vjpr]

This is implemented in v0.5.9 isn't it?

[Electroid]

Yes, this has been implemented.

[g-wozniak]

Trying either bun --hot run dev.tsx, bun --watch run dev.tsx does not do anything when modifying App.tsx and reloading (Command + R) in bun v.0.7.3.