prerender-spa-plugin/es6/index.js

Flexible, framework-agnostic static site generation for sites and SPAs built with webpack.

const path = require('path')
const Prerenderer = require('@prerenderer/prerenderer')
const PuppeteerRenderer = require('@prerenderer/renderer-puppeteer')
const { minify } = require('html-minifier')

function PrerenderSPAPlugin (...args) {
  const rendererOptions = {} // Primarily for backwards-compatibility.

  this._options = {}

  // Normal args object.
  if (args.length === 1) {
    this._options = args[0] || {}

  // Backwards-compatibility with v2
  } else {
    console.warn("[prerender-spa-plugin] You appear to be using the v2 argument-based configuration options. It's recommended that you migrate to the clearer object-based configuration system.\nCheck the documentation for more information.")
    let staticDir, routes

    args.forEach(arg => {
      if (typeof arg === 'string') staticDir = arg
      else if (Array.isArray(arg)) routes = arg
      else if (typeof arg === 'object') this._options = arg
    })

    staticDir ? this._options.staticDir = staticDir : null
    routes ? this._options.routes = routes : null
  }

  // Backwards compatiblity with v2.
  if (this._options.captureAfterDocumentEvent) {
    console.warn('[prerender-spa-plugin] captureAfterDocumentEvent has been renamed to renderAfterDocumentEvent and should be moved to the renderer options.')
    rendererOptions.renderAfterDocumentEvent = this._options.captureAfterDocumentEvent
  }

  if (this._options.captureAfterDocumentEvent) {
    console.warn('[prerender-spa-plugin] captureAfterElementExists has been renamed to renderAfterElementExists and should be moved to the renderer options.')
    rendererOptions.renderAfterElementExists = this._options.captureAfterElementExists
  }

  if (this._options.captureAfterTime) {
    console.warn('[prerender-spa-plugin] captureAfterTime has been renamed to renderAfterTime and should be moved to the renderer options.')
    rendererOptions.renderAfterTime = this._options.captureAfterTime
  }

  this._options.server = this._options.server || {}
  this._options.renderer = this._options.renderer || new PuppeteerRenderer(Object.assign({}, { headless: true }, rendererOptions))

  if (this._options.postProcessHtml) {
    console.warn('[prerender-spa-plugin] postProcessHtml should be migrated to postProcess! Consult the documentation for more information.')
  }
}

PrerenderSPAPlugin.prototype.apply = function (compiler) {
  const compilerFS = compiler.outputFileSystem

  // From https://github.com/ahmadnassri/mkdirp-promise/blob/master/lib/index.js
  const mkdirp = function (dir, opts) {
    return new Promise((resolve, reject) => {
      compilerFS.mkdirp(dir, opts, (err, made) => err === null ? resolve(made) : reject(err))
    })
  }

  const afterEmit = (compilation, done) => {
    const PrerendererInstance = new Prerenderer(this._options)

    PrerendererInstance.initialize()
      .then(() => {
        return PrerendererInstance.renderRoutes(this._options.routes || [])
      })
      // Backwards-compatibility with v2 (postprocessHTML should be migrated to postProcess)
      .then(renderedRoutes => this._options.postProcessHtml
        ? renderedRoutes.map(renderedRoute => {
          const processed = this._options.postProcessHtml(renderedRoute)
          if (typeof processed === 'string') renderedRoute.html = processed
          else renderedRoute = processed

          return renderedRoute
        })
        : renderedRoutes
      )
      // Run postProcess hooks.
      .then(renderedRoutes => this._options.postProcess
        ? Promise.all(renderedRoutes.map(renderedRoute => this._options.postProcess(renderedRoute)))
        : renderedRoutes
      )
      // Check to ensure postProcess hooks returned the renderedRoute object properly.
      .then(renderedRoutes => {
        const isValid = renderedRoutes.every(r => typeof r === 'object')
        if (!isValid) {
          throw new Error('[prerender-spa-plugin] Rendered routes are empty, did you forget to return the `context` object in postProcess?')
        }

        return renderedRoutes
      })
      // Minify html files if specified in config.
      .then(renderedRoutes => {
        if (!this._options.minify) return renderedRoutes

        renderedRoutes.forEach(route => {
          route.html = minify(route.html, this._options.minify)
        })

        return renderedRoutes
      })
      // Calculate outputPath if it hasn't been set already.
      .then(renderedRoutes => {
        renderedRoutes.forEach(rendered => {
          if (!rendered.outputPath) {
            rendered.outputPath = path.join(this._options.outputDir || this._options.staticDir, rendered.route, 'index.html')
          }
        })

        return renderedRoutes
      })
      // Create dirs and write prerendered files.
      .then(processedRoutes => {
        const promises = Promise.all(processedRoutes.map(processedRoute => {
          return mkdirp(path.dirname(processedRoute.outputPath))
            .then(() => {
              return new Promise((resolve, reject) => {
                compilerFS.writeFile(processedRoute.outputPath, processedRoute.html.trim(), err => {
                  if (err) reject(`[prerender-spa-plugin] Unable to write rendered route to file "${processedRoute.outputPath}" \n ${err}.`)
                  else resolve()
                })
              })
            })
            .catch(err => {
              if (typeof err === 'string') {
                err = `[prerender-spa-plugin] Unable to create directory ${path.dirname(processedRoute.outputPath)} for route ${processedRoute.route}. \n ${err}`
              }

              throw err
            })
        }))

        return promises
      })
      .then(r => {
        PrerendererInstance.destroy()
        done()
      })
      .catch(err => {
        PrerendererInstance.destroy()
        const msg = '[prerender-spa-plugin] Unable to prerender all routes!'
        console.error(msg)
        compilation.errors.push(new Error(msg))
        done()
      })
  }

  if (compiler.hooks) {
    const plugin = { name: 'PrerenderSPAPlugin' }
    compiler.hooks.afterEmit.tapAsync(plugin, afterEmit)
  } else {
    compiler.plugin('after-emit', afterEmit)
  }
}

PrerenderSPAPlugin.PuppeteerRenderer = PuppeteerRenderer

module.exports = PrerenderSPAPlugin