what is webpack.js
// Based on the provided configuration (webpack.config.js),
// webpack starts from the entry points and resolves each module it
// encounters while constructing the dependency graph
// entry points
// the entry point is the module that webpack uses to start building its internal dependency graph.
entry: {
'app': glob.sync('./vendor/**/*.js').concat(['./js/app.js'])
},
// output point
// the output property instructs webpack where to emit the bundle(s) and what name to use for the file(s)
output: {
filename: '[name].js',
path: path.resolve(__dirname, '../priv/static/js'),
publicPath: '/js/'
},
// dependency graph
// From the entry point, webpack will configure a set of nodes connected to one
// another as dependencies and will compile that to the output point