chore: add info about ES modules to docs #10611
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| With the warnings out of the way, this is how you activate ESM support in your tests. | ||
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| 1. Ensure you either disable [code transforms](./configuration#transform-objectstring-pathtotransformer--pathtotransformer-object) by passing `transform: {}` or otherwise configure your transformer to emit ESM rather than the default CommonJS (CJS). | ||
| 1. Execute `node` with `--experimental-vm-modules`, e.g. `node --experimental-vm-modules node_modules/.bin/jest` or `NODE_OPTIONS=--experimental-vm-modules npx jest` etc. |
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My tests for tslib didn't need these flags, just making sure that the root package json is a "type": "module" - https://github.com/microsoft/tslib/tree/master/test/esm-node-native
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@orta
That鈥檚聽because your聽tests don鈥檛聽use聽Jest, which聽runs聽tests in聽vm聽contexts, where聽the聽Module聽API needs聽that聽flag.
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Yep, see the https://nodejs.org/api/vm.html#vm_class_vm_module link above.
EDIT: Ergh, same link as @ExE-Boss posted 馃槄
Co-authored-by: Micha毛l Zasso <targos@protonmail.com>
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This might need a quick followup: the documented way of invoking with the experimental flag set through an env var does not work on Windows, requiring |
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@Pomax wanna send a PR tweaking the text to work on all platforms? |
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I don't know what your policy on "backing" third party tools is, so I have no idea what a PR would look like, here, whereas you probably do. I can heartily recommend tell folks to use cross-env for anything that relies on command line env vars if things need to work cross-platform, but I have no idea what Facebook's policy is, and I'm very much not up for signing a CLA just to submit a docs PR... though if docs PRs are exempt I can write something up? |
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I can't imagine FB having a policy on that (I don't work there). I understand not wanting the sign the CLA, if just sticking CRA just documents how to do it on different platforms, but I think that's also for educational purposes, which is not really relevant for us here: https://create-react-app.dev/docs/adding-custom-environment-variables/#adding-temporary-environment-variables-in-your-shell (they do use |
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yep, docs wise that's perfect, thanks! |
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Summary
Ref #9430 (comment)
I haven't written too much, but it's something. Added it to all
jest@26versioned docs.Test plan
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