Support emitDecoratorMetadata

[pincman]

some typescript and node framework (like nestjs) use emitDecoratorMetadata , but esbuild not support it, and @anatine/esbuild-decorators plugin can solve it .
but esbuild's transform api not support plugin,some can change the api to use build?

like the follow code

async function transpile(code, filename, options = {}) {
    const ext = path.extname(filename);

    const loaders = getLoaders(options);

    const builded = await build({
        ...commonOptions,
        platform: 'node',
        ...options,
        ...{
            loader: loaders,
            bundle: true,
            stdin: {
                sourcefile: filename,
                contents: code,
                resolveDir: path.dirname(filename),
                loader: loaders[ext],
            },
            external: [...externals, ...(options.external ?? [])],
            write: false,
            plugins: [
                ...(options.plugins ?? []),
                esbuildDecorators({ tsconfig: options.tsconfig ?? undefined }),
            ],
        },
    });
    return builded.outputFiles.map((f) => f.text).join('\n');
}

[privatenumber]

We can't use the Build API because it would bypass Node.js' resolver, and add overhead writing/reading disk.

To do what that plugin does, we don't technically need to use the Build API. We just need to re-implement the TypeScript transformation on the file when emitDecoratorMetadata is enabled.

However, this will require TypeScript to be a dependency, and add a bottleneck to transformation, which defeats the point of using esbuild (and this entire module).

Alternatively, we can consider leveraging SWC for this part but this should be investigated first. esbuild is not planning to support it.

[wenerme]

Is it possible to some how enable the tsc for this like https://github.com/thomaschaaf/esbuild-plugin-tsc ?

[privatenumber]

I'd like to reserve Issues for those interested in contributing, and discussions constructive towards addressing the issue (e.g. implementing fixes or features). Please discuss workarounds elsewhere.

[privatenumber]

@wenerme:

Is it possible to some how enable the tsc for this like thomaschaaf/esbuild-plugin-tsc ?

This is already answered above:

However, this will require TypeScript to be a dependency, and add a bottleneck to transformation, which defeats the point of using esbuild (and this entire module).

[privatenumber]

Is it that same thing as this issue? I've personally never used decorators so I'm not sure.

As I understand, what shipped in terms of tsconfig.json is support for experimentalDecorators (JS spec), rather than emitDecoratorMetadata (TS spec), which is what this thread is about.

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I published the esbuild v0.21 upgrade in tsx 4.10.0-rc.1 through the development repo (sponsors only). Holding official release for a few weeks since it's still seems to require further testing.