Bail is a bool value. This will force Webpack to exit its bundling process. It will cause Webpack to fail out on the first error instead of tolerating it. By default, Webpack will log these errors in red text in the Terminal (the browser console also, when using HMR) but will continue bundling.

To enable this option, open webpack.config.js, as follows:

module.exports = {
  bail: true
};

This will be very helpful if you want Webpack to exit a bundling process in certain circumstances. Perhaps you only want part of a project bundled. It's really up to you. Next up is caching.