How can I resolve the Jest 'Unexpected token' error when importing BufferGeometryUtils in ThreeJS?

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I'm running unit tests with Jest for a ThreeJS application and encountered an error after adding BufferGeometryUtils. My tests fail with an error about an unexpected token and a syntax issue for an import statement outside a module.

Below is the error output I received:

JAVASCRIPT
(node:34088) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)

  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    node_modules\three\examples\jsm\utils\BufferGeometryUtils.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){import { BufferAttribute, BufferGeometry, Float32BufferAttribute, InstancedBufferAttribute, InterleavedBuffer, InterleavedBufferAttribute, TriangleFanDrawMode, TriangleStripDrawMode, TrianglesDrawMode, Vector3 } from 'three';
                                                                                      ^^^^^^

    SyntaxError: Cannot use import statement outside a module

      4 | import * as jsts from 'jsts';
      5 | import * as THREE from 'three';
    > 6 | import * as BufferGeometryUtils from 'three/examples/jsm/utils/BufferGeometryUtils';
        | ^
      7 | import { bufferMiter, createPolygon, intersection, isPointInPolygon, jstsToGeoJSON, surfaceToShapes, unionLines } from './utils';
      8 |
      9 |

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1505:14)
      at Object.<anonymous> (Models/3DModels.tsx:6:1)
      at Object.<anonymous> (ProjectHeader.test.tsx:2:1)

I have already looked into common Jest configuration issues (Babel, ESM support, and transformIgnorePatterns), but I’m not sure how to proceed with this specific module import error. Any ideas on how to solve this?

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 9 days ago

Fixing BufferGeometryUtils Import Error in Jest Tests

The error you're encountering is a common issue when testing Three.js applications with Jest. The problem is that Three.js's utility modules (like BufferGeometryUtils) use ES modules syntax, but Jest by default doesn't transform files in the node_modules directory.

Solution: Configure Jest to Transform Three.js Modules

You need to modify your Jest configuration to transform the Three.js modules. Here's how to fix it:

1. Update your Jest configuration

Add or modify the transformIgnorePatterns in your Jest config (either in package.json or jest.config.js):

JAVASCRIPT
// In jest.config.js
module.exports = {
  // ... other config options
  transformIgnorePatterns: [
    "/node_modules/(?!(three|three/examples/jsm)/)"
  ]
};

Or in package.json:

JSON
"jest": {
  "transformIgnorePatterns": [
    "/node_modules/(?!(three|three/examples/jsm)/)"
  ]
}

This tells Jest to transform files from the Three.js library instead of ignoring them.

2. Make sure you have a Babel configuration

Ensure you have Babel properly configured to handle ES modules. Your .babelrc or babel.config.js should include:

JAVASCRIPT
module.exports = {
  presets: [
    ['@babel/preset-env', {targets: {node: 'current'}}],
    '@babel/preset-typescript', // if using TypeScript
    '@babel/preset-react' // if using React
  ]
};

3. Alternative: Mock BufferGeometryUtils

If you don't need the actual implementation in your tests, you can mock the module:

JAVASCRIPT
// In your setupTests.js or similar file
jest.mock('three/examples/jsm/utils/BufferGeometryUtils', () => ({
  mergeBufferGeometries: jest.fn(),
  // Add other functions you use from BufferGeometryUtils
}));

4. If using TypeScript

If you're using TypeScript, make sure your tsconfig.json has the correct module settings:

JSON
{
  "compilerOptions": {
    "esModuleInterop": true,
    "moduleResolution": "node",
    // other options...
  }
}

This approach should resolve the import error by ensuring Jest properly transforms the ES modules in the Three.js library.

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