You can do this per environment, e.g. in config/webpack/test.js:

const environment = require('./environment')
const config = environment.toWebpackConfig()
config.devtool = 'none'
module.exports = config

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

Webpacker: Disable source maps