react-native-bundle-visualizer/src/webpack.haul.extend.js

See what's inside your react-native bundle

const Visualizer = require('webpack-visualizer-plugin');
const originalConfig = require('../../../webpack.haul.js');

module.exports = function(context, config) {
	config = originalConfig(context, config);
	return Object.assign(
		{},
		config,
		{
			plugins: (config.plugins || []).concat([new Visualizer()])
		}
	);
};