feat: re-transpile excluded modules when target is es5

[klipstein]

Thanks for improving the two initial versions of the rollup-plugin-swc.

I wanted to use it in a project where I partially have to transpile to ES5 (to still support IE11) and this particular project uses quite some CommonJS node dependencies which get processed via @rollup/plugin-commonjs.

The rollup-plugin commonjs then partially generates "proxy" dependencies (which look similar to this) which need to be excluded from the initial transform(code, id), because swc cannot resolve those proxy dependencies and the build would then fail with errors like this:

[!] (plugin swc) Error: error: Unterminated string constant
  |
1 | import * as commonjsHelpers from '
  |

When those node module dependencies are excluded from swc this error disappears but then those external dependencies (which mostly are ES6 = ES2015) won't be transpiled to ES5.

It probably is an edge case, but it would be great if you include it in version 3 of rollup-plugin-swc so that I can avoid creating rollup-plugin-swc4 :)

[SukkaW]

@klipstein

Just set exclude to /node_modules/core-js then you will be able to transpile libraries under node_modules.

It is designed to let swcTransform uses rollup's transform hook so that you can transpile many files at the same time.

[klipstein]

Hi @SukkaW. This did not work for me. The commonjsHelpers is included in every commonjs module that get run through rollup plugin commonjs.

[klipstein]

@SukkaW I think I got closer to the issue. It seems that swc does not like the \0 escape that the rollup plugin commonjs generates: https://github.com/rollup/plugins/blob/master/packages/commonjs/src/helpers.js#L15

[SukkaW]

@SukkaW I think I got closer to the issue. It seems that swc does not like the \0 escape that the rollup plugin commonjs generates: https://github.com/rollup/plugins/blob/master/packages/commonjs/src/helpers.js#L15

@klipstein I might have an idea. Would you mind try this one out:

1. Install @rollup/plugin-node-resolve (npm install @rollup/plugin-node-resolve --save-dev)
2. In your rollup.config.js, add @rollup/plugin-node-resolve at the start of your plugin array.

import { nodeResolve } from '@rollup/plugin-node-resolve';
// ...
plugin: [
  nodeResolve(),
  // Your other plugins, like swc
]

Then test if commonjsHelpers is still being duplicated.

Detailed explanation: I have searched \0 in rollup plugins' repo and here is what I found:

https://github.com/rollup/plugins/blob/02fb349d315f0ffc55970fba5de20e23f8ead881/packages/node-resolve/src/index.js#L253-L261

If your test with @rollup/plugin-node-resolve success, I could add a similar approach to this plugin as well.

[klipstein]

My rollup setup is as such:

plugin: [
  nodeResolve({
      preferBuiltins: false,
      browser: true
    }),
    commonjs({
      include: ['node_modules/axios/**']
    }),
    swc(...)
]

When I replace \0 before calling transform here (https://github.com/SukkaW/rollup-plugin-swc/blob/master/src/index.ts#L107) it works:

return swcTransform(code.replace('from "\0', 'from "'), swcOption);

[klipstein]

Maybe this also helps further: https://rollupjs.org/guide/en/#conventions

There it says:

If your plugin uses 'virtual modules' (e.g. for helper functions), prefix the module ID with \0. This prevents other plugins from trying to process it.

[klipstein]

@SukkaW opened a new pull #2. Closing this.