How do I stop npm's colored output from looking ugly in Emacs term-mode?

Question

When using npm in M-x term, it generate color message like this (even with -q) :

Information from what-cursor-position

There are text properties here:
font-lock-face       (:foreground "red3" :background "black" :inverse-video nil)
fontified            t

It is ugly, and also hard to read in other themes, is it possible to change the color on the fly ? For example, change color of text that match npm http, npm ERR!

Thanks.

Containerize

Have you tried npm config set color false? – Reactionary

I didn't know that! Looks like it is more practical than make emacs change term color :) – Containerize

Yeah, I figured the same -- there are lots of Emacs libraries whose Lisp code is accessible to the relative newcomer and straightforward to customize, but term-mode is not one of those libraries. – Reactionary

So that this question doesn't hang around unanswered, I've promoted my earlier comment to an answer, and also edited the title to better reflect the sense of the question itself. – Reactionary

Answer 1

You can disable colors in npm with the command:

npm config set color false

This doesn't exactly answer your question, in that it's not a way to override ANSI colors in term-mode, but it will solve your problem, in that the npm output will no longer be ugly and hard to read.

Reactionary

You can also run your command as npm --no-color <arguments>, which is what I do in my scripts. – Rejuvenate

this answer is not working for me. npm version 6.9.0 – Acerbic

@Acerbic Works here for npm 7.4.0 (Debian buster-backports) – Dickerson

Neither config nor --no-color worked for me on Windows. – Shortening

Answer 2

I created a wrapper for npm in davidchambers/dotfiles#1. Here's the code in full:

__strip_background_colors() {
  local output="$(sed $'s:\x1B\[4[0-9]m::g')"
  [[ -n $output ]] && printf %s%s "$output" "$1"
}

npm() {
  # Strip the visually offensive background colours from npm's output,
  # leaving the foreground colours intact.
  NPM_CONFIG_COLOR=always "$(which npm)" "$@" \
    1> >(__strip_background_colors $'\n' >&1) \
    2> >(__strip_background_colors '' >&2)
}

It removes the offensive background colours while preserving the rather nice foreground colours. :)

Ahmedahmedabad

Answer 3

Since 2018:

https://github.com/npm/cli/commit/ecfbb16dc705f28aa61b3223bdbf9e47230a0fa4 config: disable color by default when $NO_COLOR is set (#19929).

Chez