transformer: enable / disable each transform instead of `target`

[sapphi-red]

esbuild has supported option that allows you to configure enable / disable each transform. There's no option like that in Oxc Transformer.

Quoting the reasons to use this option from esbuild's docs:

Here are some examples of why you might want to use this setting instead of or in addition to setting the target:

• JavaScript runtimes often do a quick implementation of newer syntax features that is slower than the equivalent older JavaScript, and you can get a speedup by telling esbuild to pretend this syntax feature isn't supported. For example, V8 has a long-standing performance bug regarding object spread that can be avoided by manually copying properties instead of using object spread syntax.
• There are many other JavaScript implementations in addition to the ones that esbuild's target setting recognizes, and they may not support certain features. If you are targeting such an implementation, you can use this setting to configure esbuild with a custom syntax feature compatibility set without needing to change esbuild itself. For example, TypeScript's JavaScript parser may not support arbitrary module namespace identifier names so you may want to turn those off when targeting TypeScript's JavaScript parser.
• You may be processing esbuild's output with another tool, and you may want esbuild to transform certain features and the other tool to transform certain other features. For example, if you are using esbuild to transform files individually to ES5 but you are then feeding the output into Webpack for bundling, you may want to preserve import() expressions even though they are a syntax error in ES5.

rolldown/rolldown#6212 also asks for this feature.

(I'm creating this issue as a placeholder, if you actually need this feature, make sure to add "👍" and describe the usecase in the comments)

[mattlewis92]

Our usecases for supported are:

• downleveling async-await for zone.js support in an angular app. Right now the only way I can see to handle this is to have esbuild post process everything that rolldown emits which isn't ideal from a performance perspective. Angular is moving away from zone.js though so longer term this won't be as relevant.
• cloudfront functions only support some modern JS features, so when bundling our functions with esbuild we use the supported option

edit: we've removed zone.js from our app so don't need support for this anymore (there are no tangible benefits for us moving from esbuild to rolldown for compiling our CF functions either)

[overlookmotel]

I'm not saying we shouldn't do this, but just to point out a potential difficulty:

Because all the transforms run in one pass, there are interactions between them. In some cases we've had to alter 1 transform to make sure it doesn't get in the way of another. It wouldn't not surprise me if some transforms implicitly rely on another transform having run before them because "I'm an ES2022 transform, so there can't be any ES2024 syntax either".

If we allow an arbitrary set of transforms, we may see some breakages. And the really tricky part is how to get good test coverage when there's many many possible combinations?

[Aquaticat]

I was building a Figma plugin. Figma plugin is made up of a backend and a frontend. The backend portion doesn't support many of the normal es features. After many many trial and errors, I finally made it work using

const createFigmaBackendConfig = (configDir: string,): UserConfig =>
  mergeConfig(createBaseConfig(configDir,), {
    esbuild: {
      supported: {
        'dynamic-import': false,
        'object-rest-spread': false,
        'top-level-await': false,
      },
    },
    build: {
      target: 'es2019',
      outDir: join('dist', 'final', 'backend',),
      lib: {
        entry: resolve(configDir, 'src', 'backend', 'index.ts',),
        name: 'index',
        fileName: 'index',
        formats: ['iife',],
      },
    },
  },);

I'm sure I might be able to make it work without the supported feature, but I'm tired.

Please implement supported if you want.