React Native Packager -------------------- React Native Packager is a project similar in scope to browserify or webpack, it provides a CommonJS-like module system, JavaScript compilation (ES6, Flow, JSX), bundling, and asset loading. The main difference is the Packager's focus on compilation and bundling speed. We aim for a sub-second edit-reload cycles. Additionally, we don't want users -- with large code bases -- to wait more than a few seconds after starting the packager. The main deviation from the node module system is the support for our proprietary module format known as `@providesModule`. However, we discourage people from using this module format because going forward we want to completely separate our infrastructure from React Native and provide an experience most JavaScript developers are familiar with, namely the node module format. We want to even go further, and let you choose your own packager and asset pipeline or even integrate into your existing infrastructure. React Native users need not to understand how the packager work, however, this documentation might be useful for advanced users and people who want to fix bugs or add features to the packager (patches welcome!). ## HTTP interface The main way you'd interact with the packager is via the HTTP interface. The following is the list of endpoints and their respective functions. ### /path/to/moduleName.bundle Does the following in order: * parse out `path/to/moduleName` * add a `.js` suffix to the path * looks in your project root(s) for the file * recursively collects all the dependencies from an in memory graph * runs the modules through the transformer (might just be cached) * concatenate the modules' content into a bundle * responds to the client with the bundle (and a SourceMap URL) ### /path/to/moduleName.map * if the package has been previously generated via the `.bundle` endpoint then the source map will be generated from that package * if the package has not been previously asked for, this will go through the same steps outlined in the `.bundle` endpoint then generate the source map. Note that source map generation currently assumes that the code has been compiled with jstransform, which preserves line and column numbers which allows us to generate source maps super fast. ### /path/to/moduleName.(map|bundle) query params You can pass options for the bundle creation through the query params, if the option is boolean `1/0` or `true/false` is accepted. Here are the current options the packager accepts: * `dev` boolean, defaults to true: sets a global `__DEV__` variable which will effect how the React Native core libraries behave. * `minify` boolean, defaults to false: whether to minify the bundle. * `runModule` boolean, defaults to true: whether to require your entry point module. So if you requested `moduleName`, this option will add a `require('moduleName')` the end of your bundle. * `inlineSourceMap` boolean, defaults to false: whether to inline source maps. ### /debug This is a page used for debugging, it offers a link to a single page : * Cached Packages: which shows you the packages that's been already generated and cached ## Programmatic API The packager is made of two things: * The core packager (which we're calling ReactPackager) * The scripts, devtools launcher, server run etc. ReactPackager is how you mainly interact with the API. ```js var ReactPackager = require('./react-packager'); ``` ### ReactPackager.buildBundle(serverOptions, bundleOptions) Builds a bundle according to the provided options. #### `serverOptions` * `projectRoots` array (required): Is the roots where your JavaScript file will exist * `blacklistRE` regexp: Is a pattern to ignore certain paths from the packager * `polyfillModuleName` array: Paths to polyfills you want to be included at the start of the bundle * `cacheVersion` string: used in creating the cache file * `resetCache` boolean, defaults to false: whether to use the cache on disk * `transformModulePath` string: Path to the module used as a JavaScript transformer * `nonPersistent` boolean, defaults to false: Whether the server should be used as a persistent deamon to watch files and update itself * `getTransformOptions` function: A function that acts as a middleware for generating options to pass to the transformer based on the bundle being built. #### `bundleOptions` * `entryFile` string (required): the entry file of the bundle, relative to one of the roots. * `dev` boolean (defaults to `true`): sets a global `__DEV__` variable which will effect how the React Native core libraries behave. * `minify` boolean: Whether to minify code and apply production optimizations. * `runModule` boolean (defaults to `true`): whether to require your entry point module. * `inlineSourceMap` boolean, defaults to false: whether to inline source maps. * `platform` string: The target platform for the build * `generateSourceMaps` boolean: Whether to generate source maps. * `sourceMapUrl` string: The url of the source map (will be appended to the bundle). ## Debugging To get verbose output when running the packager, define an environment variable: export DEBUG=ReactNativePackager:* You can combine this with other values, e.g. `DEBUG=babel,ReactNativePackager:*`. Under the hood this uses the [`debug`](https://www.npmjs.com/package/debug) package, see its documentation for all the available options. The `/debug` endpoint discussed above is also useful. ## FAQ ### Can I use this in my own non-React Native project? Yes. It's not really tied to React Native, however feature development is informed by React Native needs. ### Why didn't you use webpack? We love webpack, however, when we tried on our codebase it was slower than our developers would like it to be. You can find more discussion about the subject [here](https://github.com/facebook/react-native/issues/5).