[!] Error: Unexpected token (Note that you need plugins to import files that are not JavaScript)

[East-Apollo]

• Rollup Plugin Name: @rollup/plugin-typescript
• Rollup Plugin Version: 8.5.0
• Rollup Version: 2.79.1
• Operating System (or Browser): macOsx
• Node Version: 14.16.0
• Link to reproduction (⚠️ read below):

Expected Behavior

There are two sub projects in my project
/packages/A/src/**
/packages/shared/src/**

I referenced the shared project packages.json configuration in Project A as follows:
"devDependencies": {
"B": "workspace:*",
}

Project A refers to a method from Project shared, and I hope to build it normally

/projects/A/src/A.ts
/projects/A/rollup.config.js

/projects/shared/src/somemod.ts

// A.ts
import {theAnswer} from "shared/src/somemod";
console.log(theAnswer);

When I run the build in /projects/A/, the build failes with the described error.
[!] Error: Unexpected token (Note that you need plugins to import files that are not JavaScript)

Actual Behavior

During the actual process of building and packaging, I was constantly prompted:
[!] Error: Unexpected token (Note that you need plugins to import files that are not JavaScript)

I have already configured the relevant plugins and it is normal to directly include this method in project A. However, I envision a directory for storing public methods.

How can I solve this problem

Additional Information

[East-Apollo]

help

[potatohoney-p]

For that sibling-package layout, check both the TypeScript program and the plugin's file filter. A workspace dependency makes the import resolvable; it does not automatically make the sibling source pass the TypeScript plugin's filter.

I reproduced the error with @rollup/plugin-typescript@8.5.0 and rollup@2.79.1, using a symlinked shared package and export const theAnswer: number = 42 in its source. Running from packages/A, this configuration built and the generated CommonJS module returned 42:

packages/A/tsconfig.json:

{
  "compilerOptions": {
    "target": "ES2020",
    "module": "ESNext",
    "moduleResolution": "node",
    "strict": true,
    "rootDir": ".."
  },
  "include": ["src/**/*.ts", "../shared/src/**/*.ts"]
}

packages/A/rollup.config.js (CommonJS config):

const typescript = require('@rollup/plugin-typescript');
const { nodeResolve } = require('@rollup/plugin-node-resolve');

module.exports = {
  input: 'src/A.ts',
  output: { file: 'dist/bundle.cjs', format: 'cjs' },
  plugins: [
    nodeResolve({ extensions: ['.js', '.ts'] }),
    typescript({
      tsconfig: './tsconfig.json',
      filterRoot: '..',
      include: ['A/src/**/*.ts', 'shared/src/**/*.ts']
    })
  ]
};

Run Rollup from packages/A. The plugin include patterns above are relative to filterRoot (packages), whereas the tsconfig include paths are relative to that tsconfig (packages/A). Keep the shared package's actual name consistent with the import: your dependency snippet says B, but the import says shared.

In the reproduction, adding the sibling to tsconfig alone still left its type annotation reaching Rollup's JS parser. With both sources included, filterRoot: false also worked with the plugin's default patterns. A narrow rootDir: "src" caused a separate TS6059 diagnostic because the sibling lies outside it; use a common source root or a dedicated build tsconfig instead.

The filterRoot documentation specifically covers files outside the current working directory. These checks used TypeScript 4.9.5, node-resolve 15.0.1, tslib 2.5.0 and Linux/Node 24.22.1, not your original macOS/Node 14 environment. Your full config isn't included, so this verifies one concrete cause and fix, not every possible cause of this parser error.