# react-dev-utils This package includes some utilities used by [Create React App](https://github.com/facebook/create-react-app).
Please refer to its documentation: - [Getting Started](https://facebook.github.io/create-react-app/docs/getting-started) – How to create a new app. - [User Guide](https://facebook.github.io/create-react-app/) – How to develop apps bootstrapped with Create React App. ## Usage in Create React App Projects These utilities come by default with [Create React App](https://github.com/facebook/create-react-app). **You don’t need to install it separately in Create React App projects.** ## Usage Outside of Create React App If you don’t use Create React App, or if you [ejected](https://facebook.github.io/create-react-app/docs/available-scripts#npm-run-eject), you may keep using these utilities. Their development will be aligned with Create React App, so major versions of these utilities may come out relatively often. Feel free to fork or copy and paste them into your projects if you’d like to have more control over them, or feel free to use the old versions. Not all of them are React-specific, but we might make some of them more React-specific in the future. ### Entry Points There is no single entry point. You can only import individual top-level modules. #### `new InterpolateHtmlPlugin(htmlWebpackPlugin: HtmlWebpackPlugin, replacements: {[key:string]: string})` This webpack plugin lets us interpolate custom variables into `index.html`.
It works in tandem with [HtmlWebpackPlugin](https://github.com/ampedandwired/html-webpack-plugin) 2.x via its [events](https://github.com/ampedandwired/html-webpack-plugin#events). ```js var path = require('path'); var HtmlWebpackPlugin = require('html-webpack-plugin'); var InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin'); // webpack config var publicUrl = '/my-custom-url'; module.exports = { output: { // ... publicPath: publicUrl + '/', }, // ... plugins: [ // Generates an `index.html` file with the