entryHTML - (string) Root HTML entry point. This should be the initial HTML filename within the ./src directory. Default: 'index.html'
entryJS - (string) Root javacsript code entry point. This should be the initial Typescript filename within the ./src directory. Default: 'app.tsx'
env - (object) Key/value sets for environment variables. These environment variables will be available to your app. Default: {'NODE_ENV': process.env.NODE_ENV}
outputDir - (string) Directory where all transpiled code and static files are exported to. Default: './dist'
sourceDir - (string) Directory that includes all source files. Default: './src'
useTypescript - (boolean) Use Typescript to transpile. Otherwise use Flow. Default: false