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debug-js / debug

A tiny JavaScript debugging utility modelled after Node.js core's debugging technique. Works in Node.js and web browsers
MIT License
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debug causes npm to always issue an experimental ESM warning in node 23 #975

Open ljharb opened 2 weeks ago

ljharb commented 2 weeks ago

Specifically, https://github.com/debug-js/debug/blob/bc60914816e5e45a5fff1cd638410438fc317521/src/node.js#L32 is triggering it. See also https://github.com/nodejs/node/pull/55338#issuecomment-2411753894 and https://github.com/nodejs/node/pull/55397.

I'm not sure the best solution here. One is to use optional peer deps to force supports-color to be < 9; another is to do monkeypatching shenanigans around that require to suppress the experimental warning; I'm sure there's more.

joyeecheung commented 2 weeks ago

The warning can also be temporarily disabled using process.noDeprecation = true (it's kind of an abuse because it's an experimental warning, not a deprecation warning, and it's kind of a bug that it affects the experimental warnings, but hey the bug is out there already). A slightly saner solution can be checking whether process.version starts with v23 (the warning will be restricted to code not coming from node_modules on v22, and will probably be gone by 24).

MikeMcC399 commented 1 week ago

supports-color@9.0.0, released in Apr 2021, was the first version to use pure ESM.

This issue affects any project where supports-color >= 9.0.0 (ESM only) is installed together with debug. It is not restricted to npm.

For instance, on Ubuntu 24.04.1 LTS, Node.js 23.0.0, npm 10.9.0, executing the following:

git clone https://github.com/cypress-io/github-action
cd github-action
npm ci
node src/ping-cli.js https://example.cypress.io

not only shows the ExperimentalWarning from npm ci, it also shows the warning from 

node src/ping-cli.js https://example.cypress.io

which is not using npm at all:

$ node src/ping-cli.js https://example.cypress.io
pinging url https://example.cypress.io for 30 seconds
(node:5900) ExperimentalWarning: Support for loading ES Module in require() is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)

https://github.com/cypress-io/github-action is configured with supports-color@9.3.1, i.e. a pure ESM version.

ljharb commented 1 week ago

@MikeMcC399 however, it'd only trigger on projects that require that version, which virtually nobody would do, except in this package's case where it's treated like an implicit optional dep - requiring < 9, and importing any version, wouldn't trigger the warning.

MikeMcC399 commented 1 week ago

Under Node.js v23.1.0 the warning provides additional debugging information which confirms the previous analysis:

$ npm view npm version
(node:13088) ExperimentalWarning: CommonJS module /home/mike/n/lib/node_modules/npm/node_modules/debug/src/node.js is loading ES Module /home/mike/n/lib/node_modules/npm/node_modules/supports-color/index.js using require().
Support for loading ES Module in require() is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
10.9.0