Webpacker: JSON::ParserError: 743: unexpected token at ''

[tetherit]

Hi there,

I added webpacker using the instructions provided. I added this to my gemfile:

gem 'webpacker', github: 'rails/webpacker'

I'm using Rails 5.1.0rc1. I ran the commands:

./bin/rails webpacker:install
./bin/rails webpacker:install:react

I have made no other changes at all.

When running in development, it runs ok, but however when trying to compile the assets, I'm getting this (same error when using assets:precompile):

$ bundle exec rake webpacker:compile
Webpacker is installed 🎉 🍰
Using /data/deployer/timeline/current/config/webpack/paths.yml file for setting up webpack paths
Compiling webpacker assets 🎉
/data/deployer/timeline/current/config/webpack/shared.js:6
const { basename, join, resolve } = require('path')
      ^

SyntaxError: Unexpected token {
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:374:25)
    at Object.Module._extensions..js (module.js:417:10)
    at Module.load (module.js:344:32)
    at Function.Module._load (module.js:301:12)
    at Module.require (module.js:354:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (/data/deployer/timeline/current/config/webpack/production.js:7:22)
    at Module._compile (module.js:410:26)
    at Object.Module._extensions..js (module.js:417:10)
rake aborted!
JSON::ParserError: 743: unexpected token at ''
/var/lib/gems/2.3.0/gems/json-2.0.3/lib/json/common.rb:156:in `parse'
/var/lib/gems/2.3.0/gems/json-2.0.3/lib/json/common.rb:156:in `parse'
/data/deployer/.bundler/ruby/2.3.0/webpacker-3c488f9f4022/lib/tasks/webpacker/compile.rake:11:in `block (2 levels) in <top (required)>'
/var/lib/gems/2.3.0/gems/rake-12.0.0/exe/rake:27:in `<top (required)>'
Tasks: TOP => webpacker:compile
(See full trace by running task with --trace)

The file has not been modified at all:

$ head -n 8 /data/deployer/timeline/current/config/webpack/shared.js
// Note: You must restart bin/webpack-watcher for changes to take effect
/* eslint global-require: 0 */
/* eslint import/no-dynamic-require: 0 */

const webpack = require('webpack')
const { basename, join, resolve } = require('path')
const { sync } = require('glob')
const { readdirSync } = require('fs')

Any ideas?

[ytbryan]

I use ruby 2.4.0p0. json 2.0.3 gem. I use rails 5.1.0.rc1 and webpacker's master branch. Did webpacker:install and webpacker:install:react

It compiles successfully. Perhaps, you can try with a fresh project again to see if this persists?

This is my shared.js in case you wish to compare it.

// Note: You must restart bin/webpack-watcher for changes to take effect
/* eslint global-require: 0 */
/* eslint import/no-dynamic-require: 0 */

const webpack = require('webpack')
const { basename, join, resolve } = require('path')
const { sync } = require('glob')
const { readdirSync } = require('fs')
const ExtractTextPlugin = require('extract-text-webpack-plugin')
const ManifestPlugin = require('webpack-manifest-plugin')
const extname = require('path-complete-extname')
const { env, paths, publicPath, loadersDir } = require('./configuration.js')

const extensionGlob = `*{${paths.extensions.join(',')}}*`
const packPaths = sync(join(paths.source, paths.entry, extensionGlob))

module.exports = {
  entry: packPaths.reduce(
    (map, entry) => {
      const localMap = map
      localMap[basename(entry, extname(entry))] = resolve(entry)
      return localMap
    }, {}
  ),

  output: { filename: '[name].js', path: resolve(paths.output, paths.entry) },

  module: {
    rules: readdirSync(loadersDir).map(file => (
      require(join(loadersDir, file))
    ))
  },

  plugins: [
    new webpack.EnvironmentPlugin(JSON.parse(JSON.stringify(env))),
    new ExtractTextPlugin(env.NODE_ENV === 'production' ? '[name]-[hash].css' : '[name].css'),
    new ManifestPlugin({ fileName: 'manifest.json', publicPath, writeToFileEmit: true })
  ],

  resolve: {
    extensions: paths.extensions,
    modules: [
      resolve(paths.source),
      resolve(paths.node_modules)
    ]
  },

  resolveLoader: {
    modules: [paths.node_modules]
  }
}

[gauravtiwari]

@xanview Are you getting that error locally or during deployment to production? Are node_modules installed correctly? Just to be sure please run ./bin/yarn install to re-install deps. Which node version are you using?

I can't reproduce this locally or in production (heroku)

[renchap]

This looks like an issue with ES6 const keyword. What Node version are you using on your production environment?

[beydogan]

Upgrading from Node 5.12 to 6.10 solved the same issue for me.

[gauravtiwari]

Perhaps we document node.js version too in the readme to make sure this doesn't happen.

[gauravtiwari]

This is now documented in the readme. @xanview Feel free to close the issue.

[tetherit]

I'm running nodejs 4.2.6~dfsg-1ubuntu4.1 - I'm guessing that's the issue? - It is the latest available on chris-lea/node.js PPA which I'm guessing is deprecated?

[gauravtiwari]

Yepp 👍 Please use node >= 6.4

[rmacklin]

@gauravtiwari What changes in node 6.4 are required for this? I've successfully used it on machines with node 6.2.0. Is the requirement really >= 6.0, or is there some issue with minor versions 6.0 - 6.3 that I've just been lucky to avoid running into?

[gauravtiwari]

@rmacklin Yepp for es6 the requirement really is >= 6.0, since both versions produces identical results. Node 6.4 was more stable though in the band (6.0...6.4) so went with that to ensure everything works.

[Randall-Coding]

I had this exact same problem when running rails s

For me the solution was to simply delete my local app and pull it again from my remote repository. No issue with Node version.