Color is not preserved when setting output to stderr and stdout is redirected

[zen0wu]

I'm guessing this is due to chalk is not detecting the right stream for color support?

i = require("inquirer")
p = i.createPromptModule({ output: process.stderr })
p({ name: "value", message: "hello", type: "question" })

node test.js # this works
node test.js > test # this will show "? hello" without bold

[maxtruxa]

Just came here to report this myself. I'm running Bitwarden Cli (which uses inquirer) commands as part of a script. Interactive output from Bitwarden is sent to stderr, which is not colored if stdout is redirected.

The source of the issue is that the default chalk instance - which detects color support for stdout - is always used, even if output goes to stderr. For stderr chalk.stderr should be used.

# test.js
const chalk = require('chalk');
function isStderr(stream) {
  // Or whatever the best method of detecting stderr is.
  return stream === process.stderr;
}
function getChalkFor(stream) {
  //return chalk; // bad!
  return isStderr(stream) ? chalk.stderr : chalk;
}
function test(stream, msg) {
  const ch = getChalkFor(stream);
  stream.write(`${ch.green(msg)}\n`);
}
test(process.stdout, 'stdout');
test(process.stderr, 'stderr');

This works no matter which standard stream is redirected:

node test.js
node test.js >/dev/null
node test.js 2>/dev/null

Detecting stderr by simply comparing it with process.stderr like that is probably naive, idk.