Breaks when importing a module that uses ESM

[TaylorBeeston]

In Meteor 2.3+, importing a module that uses esm causes the server to crash with a module.export is not a function error.

I have made a minimal reproducible example here.

In that repo, I have tested and verified that Meteor 2.2.4 (the last release before Node 14) works, and 2.3 and above crash with that error.

Interestingly, this error only happens if you import an ESM package in server-side code, not on client-side code.

I imagine this issue was created by Node 14 natively supporting ESModules, but I don't have a deep enough understanding of Meteor/Reify to be able to offer any kind of fix =/

[benjamn]

@TaylorBeeston I'm no longer actively working on Meteor, but my advice to the team would be to start thinking about how the Meteor CLI can take advantage of compiling down to native ESM modules, instead of CommonJS. I'm not sure the end-to-end story is quite there yet, but it's certainly much further along than when I last worked on this stuff. Deno may be a good example to follow, though Deno is not based on Node.js. My personal bias: if I were rebuilding Meteor from scratch today, I would pick Deno as the underlying JS environment, rather than Node.js.

In the meantime, you should be able to recompile specific npm packages (to make their ESM code compatible with Node/CommonJS/Reify) using this configuration in your package.json file. You probably don't want to enable this for all npm packages in node_modules, since any work that touches (or even looks at) the entire contents of node_modules tends to be pathologically slow for large projects.

[trusktr]

Choosing Deno would be a huge breaking change, and it will introduce dependency management difficulties without an out-of-the-box package manager.

you should be able to recompile specific npm packages (to make their ESM code compatible with Node/CommonJS/Reify) using this configuration in your package.json file.

Many third-party libs not written for Meteor aren't going to all start adding meteor sections to their package.json files, so this mostly won't work, except for Meteor users who also happen to publish libs to npmjs.com.

[edemaine]

Supporting a workaround package like esm seems debatable, but what would be really nice is for Reify to support the conditional exports feature in package.json. @benjamn is this something you'd consider reviewing in a PR? It would be greatly helpful for Meteor today. Also, any pointers for how to go about it would be helpful.

[trusktr]

Note, the esm package does not support package.json exports fields.