Don't allow child scripts to manipulate terminal

[RaeesBhatti]

- Summary
create-react-app script was using ANSI to clear the screen before we could display our own information. This change disables the handing over of terminal to child script, and buffering output from it. When create-react-app detects that it is not attached to a terminal, it does not clear screen.
Fixes: netlify/cli#374

- Test plan

• npx create-react-app my-new-cra
• cd my-new-cra
• netlify dev

Before:

After:

- Description for the changelog

• Dont handover terminal to child scripts
• Buffer stdout and stderr from child scripts to terminal

- A picture of a cute animal (not mandatory but encouraged)

[DavidWells]

Looks like this removes colors from the wrapper

After

I'm wondering if this is possible while preserving child process colors... (DX etc)

[RaeesBhatti]

Since we're not connecting the stdout and stderr of our terminal to child process, create-react-app script thinks that the terminal doesn't support colors, so, it is not sending us colored output at all. While I think what you're describing is technically possible, it is incredibly tricky. NodeJS gives us three options when it comes to child-process stdio:

• inherit - what we were doing before
• pipe - what we're doing now
• ignore - you get the idea

We essentially have to create a terminal program that has a virtual terminal and manage that virtual terminal when resizing and flexing.

[swyxio]

how bout goinginto the code of strip-ansi.. and ONLY removing whatever the "clear window" characters are

[DavidWells]

That might work ¯_(ツ)_/¯

These are the chars @RaeesBhatti https://github.com/facebook/create-react-app/pull/6632/files#diff-2062ac0fbce6613dbaae936c4f6446afR15

[swyxio]

well sheet is it that easy

[RaeesBhatti]

Even if I don't call strip-ansi on the output, create-react-app still outputs un-colored text. Because we don't provide it a terminal, we provide it a buffer to write into. This is happening at chalk level, and can be tested by:

• npm i -g chalk-cli
• chalk red bold 'Unicorns & Rainbows' (will output colored text)
• chalk red bold 'Unicorns & Rainbows' > something.txt && cat something.txt (will output uncolored text)

To have any kind of control over the output means that chalk won't work.

[RaeesBhatti]

I've completely removed strip-ansi part in the latest change and the output is still uncolored. The reason is described above.

[RaeesBhatti]

Found a way to fix this, but seems like I've lost write access to this repo.

[RaeesBhatti]

With the latest change, the chalk colors and formatting is persevered.
Before latest change:

After latest change: