Phoenix Webpack.config.js Auto-Reload (Phoenix 1.4.1)

dev.exs

# the below starts on line 9 of dev.exs, the rest of the file remains unchanged
# Just npm install nodemon globally with the below command, no need to add it to package.json
# $ npm install --global nodemon
# lines 13 to 16 below are what I added to get this to work
# lines 17 to 23 are already there with a new install (do not delete them, just add nodemon stuff before it)

config :my_app, MyAppWeb.Endpoint,
  http: [port: 4000],
  debug_errors: true,
  code_reloader: true,
  check_origin: false,
  watchers: [
    nodemon: [
      "--watch",
      "webpack.config.js",
      "--exec",
      "node_modules/webpack/bin/webpack.js",
      "--mode",
      "development",
      "--watch-stdin",
      cd: Path.expand("../assets", __DIR__)
    ]
  ]

This is what the top of dev.exs looks like in a new install

config :my_app, MyAppWeb.Endpoint,
  http: [port: 4000],
  debug_errors: true,
  code_reloader: true,
  check_origin: false,
  watchers: [
    node: [
      "node_modules/webpack/bin/webpack.js",
      "--mode",
      "development",
      "--watch-stdin",
      cd: Path.expand("../assets", __DIR__)
    ]
  ]

This is what you need to change it to for Webpack to auto-reload with the new settings after you modify config files

config :my_app, MyAppWeb.Endpoint,
  http: [port: 4000],
  debug_errors: true,
  code_reloader: true,
  check_origin: false,
  watchers: [
    nodemon: [
      "--watch",
      "webpack.config.js",
      "--exec",
      "node_modules/webpack/bin/webpack.js",
      "--mode",
      "development",
      "--watch-stdin",
      cd: Path.expand("../assets", __DIR__)
    ]
  ]

Just install nodemon globally and you are good to go (Phoenix 1.4.1)