create_chunkhash_stubs_on_build.js

/**
 * Merge this in your nuxt.config.js or copy to examples/hello-world
 * yarn build
 * yarn start
 * open index in browser (dont click About)
 * edit and change pages/about.vue
 * yarn build && yarn start
 * click About in browser
 * => page reloads
 */
import { resolve } from 'path'
import fs from 'fs'
import { promisify } from 'util'

const readDir = promisify(fs.readdir)
const readFile = promisify(fs.readFile)

let previousWebpackChunks = {}

// maybe better to use save-eval package?
const saferEval = (window, code) => {
  "use strict"
  let l
  try {
    eval(code)
  } catch(e) {
    // ignore potential errors
  }
}

export default {
  hooks: {
    build: {
      async before(builder, buildOptions) {
        const chunksPath = resolve(builder.nuxt.options.buildDir, 'dist', 'client')
        
        if (fs.existsSync(chunksPath)) {
          const chunkFiles = (await readDir(chunksPath)).filter(file => file.endsWith('.js'))
          if (chunkFiles) {
            await Promise.all(chunkFiles.map(async (file) => {
              const window = {}
              const webpackCode = await readFile(resolve(chunksPath, file), 'utf8')
              // only page chunks
              if (webpackCode.startsWith('(window.webpackJsonp')) {
                saferEval(window, webpackCode)
                const data = window.webpackJsonp.map((chunk) => {
                  const codeBlocks = {}
                  Object.keys(chunk[1]).forEach((id) => {
                    codeBlocks[id] = 'fnReload'
                  })
                  return [
                    chunk[0],
                    codeBlocks
                  ]
                })
                previousWebpackChunks[file] = data
              }
            }))
          }
        }
      },
      done: (builder) => {
        const chunksPath = resolve(builder.nuxt.options.buildDir, 'dist', 'client')
        if (fs.existsSync(chunksPath)) {
          Object.keys(previousWebpackChunks).forEach((file) => {
            const filePath = resolve(chunksPath, file)
            if (!fs.existsSync(filePath)) {
              const jsCode = previousWebpackChunks[file].reduce((acc, value) => {
                acc += '(window.webpackJsonp=window.webpackJsonp||[]).push('
                acc += JSON.stringify(value).replace(/['"]fnReload['"]/g, 'function(){window.location.reload(true)}')
                acc += ');'
                return acc
              }, '')
              fs.writeFileSync(filePath, jsCode + 'window.location.reload(true);')
            }
          })
        }
      }
    }
  }
}