improve comments in server.js

Author: yyx990803

server.js

@@ -9,31 +9,30 @@ const compression = require('compression')
 const serialize = require('serialize-javascript')
 const resolve = file => path.resolve(__dirname, file)
 
-// https://github.com/vuejs/vue/blob/next/packages/vue-server-renderer/README.md#why-use-bundlerenderer
-const createBundleRenderer = require('vue-server-renderer').createBundleRenderer
-
 const app = express()
 
-// setup the server renderer, depending on dev/prod environment
-let html, renderer
+let indexHTML // generated by html-webpack-plugin
+let renderer // created from the webpack-generated server bundle
 if (isProd) {
- // create server renderer and index HTML from real fs
- const bundlePath = resolve('./dist/server-bundle.js')
- renderer = createRenderer(fs.readFileSync(bundlePath, 'utf-8'))
- html = parseIndex(fs.readFileSync(resolve('./dist/index.html'), 'utf-8'))
+ // in production: create server renderer and index HTML from real fs
+ renderer = createRenderer(fs.readFileSync(resolve('./dist/server-bundle.js'), 'utf-8'))
+ indexHTML = parseIndex(fs.readFileSync(resolve('./dist/index.html'), 'utf-8'))
 } else {
+ // in development: setup the dev server with watch and hot-reload,
+ // and update renderer / index HTML on file change.
  require('./build/setup-dev-server')(app, {
  bundleUpdated: bundle => {
  renderer = createRenderer(bundle)
  },
  indexUpdated: index => {
- html = parseIndex(index)
+ indexHTML = parseIndex(index)
  }
  })
 }
 
 function createRenderer (bundle) {
- return createBundleRenderer(bundle, {
+ // https://github.com/vuejs/vue/blob/next/packages/vue-server-renderer/README.md#why-use-bundlerenderer
+ return require('vue-server-renderer').createBundleRenderer(bundle, {
  cache: require('lru-cache')({
  max: 1000,
  maxAge: 1000 * 60 * 15
@@ -65,7 +64,7 @@ app.get('*', (req, res) => {
  const renderStream = renderer.renderToStream(context)
 
  renderStream.once('data', () => {
- res.write(html.head)
+ res.write(indexHTML.head)
  })
 
  renderStream.on('data', chunk => {
@@ -81,7 +80,7 @@ app.get('*', (req, res) => {
  }</script>`
  )
  }
- res.end(html.tail)
+ res.end(indexHTML.tail)
  console.log(`whole request: ${Date.now() - s}ms`)
  })