transformer: research inserting helper methods with import or require

[Boshen]

cjs vs esm 😡

[overlookmotel]

Helper methods should already inserted as import statements / require depending on source_type. What's missing?

[Boshen]

Babel uses numerous conditions to decide on what to insert: https://github.com/babel/babel/blob/54a8389fa31ce4fd18b0335b05832dc1ad3cc21f/packages/babel-helper-module-imports/src/import-injector.ts#L20-L78

[Boshen]

There is one failing test case in monitor-oxc due to this confusion:

file:///home/runner/work/monitor-oxc/monitor-oxc/node_modules/.pnpm/@[email protected][email protected]/node_modules/@azure/core-rest-pipeline/dist/esm/policies/proxyPolicy.js:2
import { HttpProxyAgent } from "http-proxy-agent";
         ^^^^^^^^^^^^^^
SyntaxError: The requested module 'http-proxy-agent' does not provide an export named 'HttpProxyAgent'
    at ModuleJob._instantiate (node:internal/modules/esm/module_job:171:21)
    at async ModuleJob.run (node:internal/modules/esm/module_job:254:5)
    at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:482:26)
    at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:117:5)

We inserted the wrong import in one of the files in http-proxy-agent

[overlookmotel]

I'm confused. Our transforms only insert imports from @babel/runtime and react. We didn't insert that import.

It's present in the original source:

https://www.npmjs.com/package/@azure/core-rest-pipeline?activeTab=code

[Boshen]

The transformer transformed files in http-proxy-agent, which breaks node.js because it cannot detect esm anymore.

It has nothing to do with the importer file.

[Boshen]

Actual offending file: https://cdn.jsdelivr.net/npm/[email protected]/dist/index.js

I need to figure out why it's set as a module

oxc/crates/oxc_transformer/src/common/module_imports.rs

Lines 157 to 164 in 6e48059

	/// Insert `import` / `require` statements at top of program.
	fn insert_into_program(&self, transform_ctx: &TransformCtx<'a>, ctx: &mut TraverseCtx<'a>) {
	if transform_ctx.source_type.is_script() {
	self.insert_require_statements(transform_ctx, ctx);
	} else {
	self.insert_import_statements(transform_ctx, ctx);
	}
	}

[Boshen]

oxc/crates/oxc_span/src/source_type/mod.rs

Line 472 in 6e48059

"js" | "mjs" | "jsx" => (Language::JavaScript, ModuleKind::Module),

If we want to make this proper, we need to start .js as Unambiguous ... that'll be a lot of things to fix 🤔

[overlookmotel]

I still don't get what's going on in that failing test with http-proxy-agent. So maybe I'm missing the point again, but...

In monitor-oxc, shouldn't we be determining whether a file is ESM or CommonJS by looking for a type field package.json? This code is running in NodeJS, so there should be no ambiguity, and no need to search the code for import / export statements to make a guess.

In the case of http-proxy-agent there is no type field present in package.json, so it should be treated as CommonJS.