webpack.config.hasher.js

// https://github.com/webpack/webpack/issues/86#issuecomment-179957661

// in index.pug, write simply [[app]] if your JS is app.js

var webpack = require('webpack')
var path = require('path')
var fs = require('fs')

module.exports = {
  entry: {
    app: './front/app.js'
  },
  output: {
    path: path.join(__dirname, 'public'),
    filename: 'js/app-[chunkhash:8].js',
    publicPath: '/'
  },
  plugins: [
    // ...    
    function () {
      this.plugin('done', function (statsData) {
        var stats = statsData.toJson()

        if (!stats.errors.length) {
          var templateFileName = 'front/views/index.pug'
          var template = fs.readFileSync(path.join(__dirname, templateFileName), 'utf8')

          var fileReplaceRegex = /\[\[([\w-]*)\]\]/g
          var matches = template.match(fileReplaceRegex)
          for (var i = 0; i < matches.length; i++) {
            var placeholderString = matches[i]
            var fileName = placeholderString.replace(fileReplaceRegex, '$1')
            var hashedFileName = stats.assetsByChunkName[fileName][0]
            template = template.replace(placeholderString, '\'' + hashedFileName + '\'')
          }

          fs.writeFileSync(path.join(__dirname, 'public/index.pug'), template)
        }
      })
    }
  ],
  // ...
}