How to write Jest transformIgnorePatterns

Question

I have this excpetion

Jest encountered an unexpected token

    This usually means that you are trying to import a file which Jest cannot parse, e.g. it\'s not p         


        

Answer 1

I had a similar error while working on a project with jest, webpack, and vanilla js, so that error is thrown when jest encounters this line of code import '../css/styles.css'; in any /*?.js$/ file. I solved it by moving the jest configurations from the package.json file into a jest.config.js file with the following minimal configuration;

// jest.config.js
module.exports = 
  "moduleNameMapper": {
    "\\.(css|less|scss)$": "identity-obj-proxy"
  }
}

Then in babel.config.js

module.exports = {
  presets: [
    [
      '@babel/preset-env',
      {
        targets: {
          node: 'current',
        },
      },
    ],
  ],
};