Add --watch flag to the build command

[DCzajkowski]

Use case

Sometimes I want to create a simple playground for experimentation and pulling Webpack or Parcel seems like an overkill.

Also, it's not that easy to set up Webpack or Parcel to listen on config file changes (and this is where most of the changes happen anyway.)

For those situations Tailwind provides tailwindcss build, but it runs just once — there is no way to listen to changes.

Current scenario

1. Set up Parcel or whatever build tool you are into
2. Run it in a watch mode
3. Write some HTML
4. Find out a utilities' variant is disabled
5. Go to the tailwind.config.js, edit and save
6. Go to app.css, save (so that the build is retriggered)
7. Preview the changes in the browser

Proposed solution

It would be cool to have tailwindcss build --watch so that manual builds or external tools are not required.

1. Run tailwindcss build app.css -o dist/app.css --watch
2. Write some HTML
3. Find out a utilities' variant is disabled
4. Go to the tailwind.config.js, edit and save
5. Preview the changes in the browser

Firstly, there is two steps less. Profit! But most importantly, there is no need to setup any external tools which saves time and decreases friction 💸

Summary

I have already implemented the --watch flag and I was wondering if anyone is interested in this 😄 If there is positive feedback, I'll post a PR 💪

Here is a demo (external link to streamable):

[DCzajkowski]

Update: The first attempt at the implementation was made here.
As @​adamwathan suggested here, I will try to create a thin wrapper around postcss cli, instead of using a custom solution.