tty: truecolor check moved before 256 check by duncanhealy · Pull Request #30474 · nodejs/node · GitHub

256 color would be return instead of 16m if both env variables were set
Test added to pseudo-tty/test-tty-color-support
Related Issue: #27609

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
documentation is changed or added
commit message follows commit guidelines

LGTM. Thanks for the fix!

CI: https://ci.nodejs.org/job/node-test-pull-request/26571/

I looks like this if statement can be removed, if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit') { /* ... */ } is sufficient.

Hi @lpinca this is to catch the case when no TERM environment variable is set
without this COLORS_2 is returned which fails an existing test

I don't get it, if env.COLORTERM is truthy, COLORS_16m is returned only if env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit' otherwise nothing is done so why not using only

if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
  return COLORS_16m;

COLORTERM can be set to values other than truecolor and 24bit . yes no gnome-terminal are other values used. We want to return the higest spec tty capability available first. If you remove the second check for env.COLORTERM you miss the case when TERM is not set but COLORTERM is not truecolor or 24bit. If you leave the code as it was before you get 256 color terminal when your terminal is capable of 16M. Basically we are moving the COLORS_256 check inbetween the COLORS_16m and the COLORS_16 checks

FWIW this is what I'm suggesting

diff --git a/lib/internal/tty.js b/lib/internal/tty.js
index faf5df9b42..63832ef220 100644
--- a/lib/internal/tty.js
+++ b/lib/internal/tty.js
@@ -173,6 +173,9 @@ function getColorDepth(env = process.env) {
       return COLORS_256;
   }
 
+  if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
+    return COLORS_16m;
+
   if (env.TERM) {
     if (/^xterm-256/.test(env.TERM))
       return COLORS_256;
@@ -188,13 +191,10 @@ function getColorDepth(env = process.env) {
       }
     }
   }
-
+  // Move 16 color COLORTERM below 16m and 256
   if (env.COLORTERM) {
-    if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
-      return COLORS_16m;
     return COLORS_16;
   }
-
   return COLORS_2;
 }
 
diff --git a/test/pseudo-tty/test-tty-color-support.js b/test/pseudo-tty/test-tty-color-support.js
index b2cfc804c3..57ed640d4d 100644
--- a/test/pseudo-tty/test-tty-color-support.js
+++ b/test/pseudo-tty/test-tty-color-support.js
@@ -71,6 +71,7 @@ const writeStream = new WriteStream(fd);
   [{ NO_COLOR: '', COLORTERM: '24bit' }, 1],
   [{ TMUX: '1', FORCE_COLOR: 0 }, 1],
   [{ NO_COLOR: 'true', FORCE_COLOR: 0, COLORTERM: 'truecolor' }, 1],
+  [{ TERM: 'xterm-256color', COLORTERM: 'truecolor' }, 24],
 ].forEach(([env, depth], i) => {
   const actual = writeStream.getColorDepth(env);
   assert.strictEqual(

if (env.COLORTERM) {
  if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
    return COLORS_16m;
}

is equal to

if (
  env.COLORTERM &&
  (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
) {
  return COLORS_16m;
}

which is equal to

if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit') {
  return COLORS_16m;
}

if you remove the bottom if and make test you can see the case when it fails

I've applied the patch in my previous comment and tests pass.

What you mean with bottom if? The one on line 197? If so I'm not suggesting to remove it. I never did. Anyway it does not matter, it is not very important :)

ok yes we can remove the nested if - I thought you were talking about the second if (env.COLORTERM) - I'll update the pull request now

CI: https://ci.nodejs.org/job/node-test-pull-request/26670/

Landed in 80ac428, thanks for the PR! 🎉

256 color would be return instead of 16m if both env variables were set * tty: improve color check order highest spec first * tty: add test for TERM and COLORTERM set * tty: move COLORTERM check outside TERM closure * tty: remove extra if check for COLORTERM Refs: #27609 PR-URL: #30474 Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Richard Lau <riclau@uk.ibm.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

duncanhealy added 3 commits November 13, 2019 17:59

tty: improve color check order highest spec first

9f3139c

tty: add test for TERM and COLORTERM set

4cd885f

tty: move COLORTERM check outside TERM closure

7dde89e

nodejs-github-bot added the tty Issues and PRs related to the tty subsystem. label Nov 13, 2019

BridgeAR approved these changes Nov 13, 2019

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richardlau approved these changes Nov 13, 2019

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BridgeAR added the author ready PRs that have at least one approval, no outstanding review comments, and a CI started. label Nov 13, 2019

cjihrig approved these changes Nov 13, 2019

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jasnell approved these changes Nov 14, 2019

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lpinca reviewed Nov 15, 2019

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tty: remove extra if check for COLORTERM

7df205f

lpinca approved these changes Nov 17, 2019

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addaleax closed this Nov 27, 2019

BridgeAR mentioned this pull request Dec 3, 2019

v13.3.0 proposal #30774

Merged

BethGriggs mentioned this pull request Dec 9, 2019

v12.13.2 proposal #30865

Closed

BethGriggs mentioned this pull request Dec 23, 2019

v12.14.1 proposal #31069

Merged

Mesteery mentioned this pull request Aug 10, 2021

Update terminal environment variables to detect colors #27609

Closed

jacobcxdev mentioned this pull request Mar 23, 2026

tty.WriteStream.getColorDepth() returns 8 inside tmux despite COLORTERM=truecolor #62404

Closed

tty: truecolor check moved before 256 check by duncanhealy · Pull Request #30474 · nodejs/node · GitHub

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tty: truecolor check moved before 256 check - #30474

tty: truecolor check moved before 256 check#30474duncanhealy wants to merge 4 commits intonodejs:masternodejs/node:masterfrom duncanhealy:truecolor-before-256duncanhealy/node:truecolor-before-256Copy head branch name to clipboard

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tty: truecolor check moved before 256 check#30474
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