# babel-jest [Babel](https://github.com/babel/babel) [jest](https://github.com/facebook/jest) plugin ## Usage If you are already using `jest-cli`, add `babel-jest` and it will automatically compile JavaScript code using Babel. ```bash yarn add --dev babel-jest @babel/core ``` If you would like to write your own preprocessor, uninstall and delete babel-jest and set the [config.transform](https://jestjs.io/docs/configuration#transform-object-string-string) option to your preprocessor. ## Setup _Note: this step is only required if you are using `babel-jest` with additional code preprocessors._ To explicitly define `babel-jest` as a transformer for your JavaScript code, map _.js_ files to the `babel-jest` module. Typescript files are also supported. ```json "transform": { "^.+\\.[t|j]sx?$": "babel-jest" }, ```