[BUG] Node.js 16 results in DeprecationWarning: Use of deprecated folder mapping "./" in the "exports" field with file import

[zdm]

Current exports syntax is not compatible with node 15.

(node:12200) [DEP0148] DeprecationWarning: Use of deprecated folder mapping "./" in the "exports" field module resolution of the package at C:\Users\zdm\.node_modules\playwright-chromium\package.json.
Update this package.json to use a subpath pattern like "./*".

You need to update to the new rules or remove this section.

New rules should looks like this:

"exports": {
    ".": {
      "import": "./index.mjs",
      "require": "./index.js"
    },
    "./*": "./*.js"
  },

[pavelfeldman]

Where do you see this message and this line? Could you provide the steps to reproduce? It does not complain on node/15.13 + npm/7.7.6 for me.

[zdm]

try this code:

require( "playwright-chromium/lib/client/page" );

I need to add custom methods to the Page class prototype, so I need to require client/page directly.
In any case current folders export synax is already deprecated and you need to update it.

[pavelfeldman]

require( "playwright-chromium/lib/client/page" );

Works for me on the node / npm versions i mentioned above. Are there any steps I can follow to reproduce this?

[zdm]

You need to perform require from the external script or package.

[pavelfeldman]

You need to perform require from the external script or package.

That's what I did. Node changed its mind on the deprecation:

nodejs/node#35747
nodejs/node#36859

What is your Node 15 version? Is it recent?

[zdm]

here is the link to the specification, where this api marked as deprecated.
https://nodejs.org/api/packages.html#packages_subpath_folder_mappings

[zdm]

my node - 5.13.0

[zdm]

sorry, 15.13.0 ))

[pavelfeldman]

I'm on macOS, v15.13.0, I have a single dependency in my node_modules, which is playwright. My index file in the root folder is:

require( "playwright/lib/client/page" );

and I can run it ok. If I add a non-default --pending-deprecation flag I get your warning, but I don't get it without it. Are you by any chance running it with pending deprecations flag?

[pavelfeldman]

As https://nodejs.org/api/deprecations.html#deprecations_dep0148_folder_mappings_in_exports_trailing states,

Without --pending-deprecation, runtime warnings occur only for exports resolutions not in node_modules.
This means there will not be deprecation warnings for "exports" in dependencies.

Are you using playwright outside of the node_modules?

[zdm]

adAhh, sorry.
Node was updated today to 15.13.0 and this warning had gone.
It was present on node 15.12.0.

[zdm]

Yes, i installed playwright globally.

[pavelfeldman]

Globally is still via node_modules, so we are good. Ok then, closing as not an issue!

[zdm]

The issue is still present under node 15.13.0.

Way to reproduce:

1. playwright-chromium installed globally;
2. node 15.13.0;

const { Page } = require( "playwright-chromium/lib/client/page" );

( async () => {} )();

[mxschmitt]

I also tried to reproduce, but was not successful in it. As far as I know its required to set the NODE_PATH environment variable to your global node_modules directory, otherwise global imports via require won't work. Did you do this? Also having it reproducible via Docker would be useful and help a lot. Thanks!

[zdm]

no, I haven't set NODE_PATH, this is not required.
all, what I did to make global modules loadable:

ln -s ~/.npm/lib/node_modules ~/.node_modules

[zdm]

I think we need to just update exports to the new syntax.
Current style is deprecated and will not work in the next versions.

[mxschmitt]

Try to set NODE_PATH to your global node_modules (see npm list -g --depth=0 and add there node_modules) folder. Your current approach messes probably some internals up.

[zdm]

I tested, this not helped.
Could we just update ./ : "./" to ./*: "./*.js" and forget about this?
I checked, new syntax works for the latest and lts node releases.

[pavelfeldman]

Since global installs are discouraged, we are unlikely to address it before it becomes a real issue in Node. So far, this deprecation is reversed and I suspect it might vanish altogether because it is hard to change entire npm ecosystem at will. Let's see in what form it makes its way into LTS and revisit it.

[zdm]

Hi,
In node v16 deprecation warning is shown all the times:

(node:129593) [DEP0148] DeprecationWarning: Use of deprecated folder mapping "./" in the "exports" field module resolution of the package at /mnt/hgfs/projects/devel/crawlsy/node_modules/playwright-core/package.json.
Update this package.json to use a subpath pattern like "./*".

(SEMVER-MAJOR) module: runtime deprecate subpath folder mappings (Antoine du Hamel) #37215
nodejs/node#37215

It's time to update. )

[mxschmitt]

I was able to reproduce this, since there are no Node.js 16 docker images yet I had to manually install:

docker run -it ubuntu:focal /bin/bash
curl -fsSL https://deb.nodesource.com/setup_16.x | bash 
apt-get install -y nodejs
mkdir test
cd test
npm init -y
npm install playwright-chromium
cat > foo.js <<- EOM
const { Page } = require( "playwright-chromium/lib/client/page" );
EOM
node foo.js

Which results as pointed out in:

(node:3895) [DEP0148] DeprecationWarning: Use of deprecated folder mapping "./" in the "exports" field module resolution of the package at /test/node_modules/playwright-chromium/package.json.
Update this package.json to use a subpath pattern like "./*".
(Use `node --trace-deprecation ...` to show where the warning was created)

[mxschmitt]

Closing for now, nobody reported any issues.

[zdm]

This was not fixed!
Your pull request wasn't applied.

[mxschmitt]

See the comment in the pull request. A lot of package maintainers need to deal with it and the only option to have no warning is to break older node versions.

We are waiting for more users to face into that problem.

[zdm]

Did you tested with the old versions?
I tested with the current LTS version - it works.
What is the minimal version that you are want to support?

[mxschmitt]

See the GitHub Action run on the pull request.

[zdm]

In nodejs v17 current exports not working anymore.

[36e2ffe6dc] - (SEMVER-MAJOR) module: subpath folder mappings EOL (Guy Bedford) #40121
[64287e4d45] - (SEMVER-MAJOR) module: runtime deprecate trailing slash patterns (Guy Bedford) #40117

Could you pls add "./*": "./*" pattern.

[arprinceofficial]

(node:6112) [DEP0155] DeprecationWarning: Use of deprecated trailing slash pattern mapping "./" in the "exports" field module resolution of the package at D:\Github Projects\emasbd\emasbd_frontend\node_modules\flowbite-vue\package.json imported from D:\Github Projects\emasbd\emasbd_frontend\node_modules. Mapping specifiers ending in "/" is no longer supported.
(Use node --trace-deprecation ... to show where the warning was created)

(node:6112) [DEP0166] DeprecationWarning: Use of deprecated double slash resolving "./dist//index.mjs" for module request ".//index.mjs" matched to "./*" in the "exports" field module resolution of the package at D:\Github Projects\emasbd\emasbd_frontend\node_modules\flowbite-vue\package.json imported from D:\Github Projects\emasbd\emasbd_frontend\node_modules.

pls help me for getting this warning