Added link=“prefetch” tags

package.json

@@ -200,6 +200,7 @@
     "nodemon": "1.11.0",
     "prettier": "1.8.2",
     "raf": "^3.4.0",
-    "react-test-renderer": "^16.1.0"
+    "react-test-renderer": "^16.1.0",
+    "webpack-manifest-plugin": "^1.3.2"
   }
 }

server/pages/components/Layout.js

@@ -5,6 +5,7 @@ import { TopNavigation, BottomNavigation } from './Navigation';
 import Analytics from '../../../shared/components/Analytics';
 import globalStyles from '../../../shared/styles/globals';
 import { color } from '../../../shared/styles/constants';
+import prefetchTags from '../../utils/prefetchTags';
 
 type Props = {
   children?: React$Element<*>,
@@ -40,10 +41,7 @@ export default function Layout({ children }: Props) {
             href="/favicon-32.png"
             sizes="32x32"
           />
-          <link
+          {prefetchTags}
-            rel="dns-prefetch"
-            href={process.env.AWS_S3_UPLOAD_BUCKET_URL}
-          />
         </Helmet>
         <Analytics />
 

server/utils/prefetchTags.js

@@ -0,0 +1,33 @@
+// @flow
+import React from 'react';
+import webpackConfig from '../../webpack.config';
+
+const PUBLIC_PATH = webpackConfig.output.publicPath;
+
+const prefetchTags = [
+  <link rel="dns-prefetch" href={process.env.AWS_S3_UPLOAD_BUCKET_URL} />,
+];
+
+if (process.env.NODE_ENV === 'production') {
+  try {
+    const manifest = require('../../dist/manifest.json');
+    Object.values(manifest).forEach(filename => {
+      if (typeof filename !== 'string') return;
+      if (filename.endsWith('.js')) {
+        prefetchTags.push(
+          <link rel="prefetch" href={`${PUBLIC_PATH}${filename}`} as="script" />
+        );
+      } else if (filename.endsWith('.css')) {
+        prefetchTags.push(
+          <link rel="prefetch" href={`${PUBLIC_PATH}${filename}`} as="style" />
+        );
+      }
+    });
+  } catch (_e) {
+    console.warn(
+      'Warning: Unable to load dist/manifest.json. Please `yarn build` before starting production server'
+    );
+  }
+}
+
+export default prefetchTags;

webpack.config.dev.js

@@ -16,12 +16,13 @@ const developmentWebpackConfig = Object.assign(commonWebpackConfig, {
   ],
 });
 
-developmentWebpackConfig.plugins.push(new ExtractTextPlugin({ filename: 'styles.css' }));
+developmentWebpackConfig.plugins = [
-developmentWebpackConfig.plugins.push(new webpack.HotModuleReplacementPlugin());
+  ...developmentWebpackConfig.plugins,
-developmentWebpackConfig.plugins.push(
+  new ExtractTextPlugin({ filename: 'styles.css' }),
+  new webpack.HotModuleReplacementPlugin(),
   new HtmlWebpackPlugin({
     title: 'Outline',
-  })
+  }),
-);
+];
 
 module.exports = developmentWebpackConfig;

webpack.config.prod.js

@@ -3,6 +3,7 @@ var path = require('path');
 var webpack = require('webpack');
 var HtmlWebpackPlugin = require('html-webpack-plugin');
 var ExtractTextPlugin = require('extract-text-webpack-plugin');
+var ManifestPlugin = require('webpack-manifest-plugin');
 
 commonWebpackConfig = require('./webpack.config');
 
@@ -17,27 +18,23 @@ productionWebpackConfig = Object.assign(commonWebpackConfig, {
   },
   stats: "normal"
 });
-productionWebpackConfig.plugins.push(
+productionWebpackConfig.plugins = [
+  ...productionWebpackConfig.plugins,
+  new ManifestPlugin(),
   new HtmlWebpackPlugin({
     template: 'server/static/index.html',
-  })
+  }),
-);
+  new ExtractTextPlugin({ filename: 'styles.[hash].css' }),
-productionWebpackConfig.plugins.push(
-  new ExtractTextPlugin({ filename: 'styles.[hash].css' })
-);
-productionWebpackConfig.plugins.push(
   new webpack.optimize.UglifyJsPlugin({
     sourceMap: true,
-  })
+  }),
-);
-productionWebpackConfig.plugins.push(
   new webpack.DefinePlugin({
     'process.env': {
       URL: JSON.stringify(process.env.URL),
       NODE_ENV: JSON.stringify('production'),
       GOOGLE_ANALYTICS_ID: JSON.stringify(process.env.GOOGLE_ANALYTICS_ID),
     },
-  })
+  }),
-);
+];
 
 module.exports = productionWebpackConfig;

yarn.lock

@@ -3612,6 +3612,16 @@ fs-exists-sync@^0.1.0:
   version "0.1.0"
   resolved "https://registry.yarnpkg.com/fs-exists-sync/-/fs-exists-sync-0.1.0.tgz#982d6893af918e72d08dec9e8673ff2b5a8d6add"
 
+fs-extra@^0.30.0:
+  version "0.30.0"
+  resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-0.30.0.tgz#f233ffcc08d4da7d432daa449776989db1df93f0"
+  dependencies:
+    graceful-fs "^4.1.2"
+    jsonfile "^2.1.0"
+    klaw "^1.0.0"
+    path-is-absolute "^1.0.0"
+    rimraf "^2.2.8"
+
 fs-extra@^4.0.0, fs-extra@^4.0.1:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-4.0.1.tgz#7fc0c6c8957f983f57f306a24e5b9ddd8d0dd880"
@@ -3922,7 +3932,7 @@ graceful-fs@^3.0.0, graceful-fs@~3.0.2:
   dependencies:
     natives "^1.1.0"
 
-graceful-fs@^4.1.11, graceful-fs@^4.1.2, graceful-fs@^4.1.6:
+graceful-fs@^4.1.11, graceful-fs@^4.1.2, graceful-fs@^4.1.6, graceful-fs@^4.1.9:
   version "4.1.11"
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.11.tgz#0e8bdfe4d1ddb8854d64e04ea7c00e2a026e5658"
 
@@ -5369,6 +5379,12 @@ json5@^0.5.0, json5@^0.5.1:
   version "0.5.1"
   resolved "https://registry.yarnpkg.com/json5/-/json5-0.5.1.tgz#1eade7acc012034ad84e2396767ead9fa5495821"
 
+jsonfile@^2.1.0:
+  version "2.4.0"
+  resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-2.4.0.tgz#3736a2b428b87bbda0cc83b53fa3d633a35c2ae8"
+  optionalDependencies:
+    graceful-fs "^4.1.6"
+
 jsonfile@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-3.0.1.tgz#a5ecc6f65f53f662c4415c7675a0331d0992ec66"
@@ -5468,6 +5484,12 @@ kind-of@^4.0.0:
   dependencies:
     is-buffer "^1.1.5"
 
+klaw@^1.0.0:
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/klaw/-/klaw-1.3.1.tgz#4088433b46b3b1ba259d78785d8e96f73ba02439"
+  optionalDependencies:
+    graceful-fs "^4.1.9"
+
 koa-bodyparser@4.2.0:
   version "4.2.0"
   resolved "https://registry.yarnpkg.com/koa-bodyparser/-/koa-bodyparser-4.2.0.tgz#bce6e08bc65f8709b6d1faa9411c7f0d8938aa54"
@@ -6086,7 +6108,7 @@ lodash.values@^4.3.0:
   version "4.3.0"
   resolved "https://registry.yarnpkg.com/lodash.values/-/lodash.values-4.3.0.tgz#a3a6c2b0ebecc5c2cba1c17e6e620fe81b53d347"
 
-lodash@^4.0.0, lodash@^4.11.1, lodash@^4.13.1, lodash@^4.14.0, lodash@^4.15.0, lodash@^4.17.0, lodash@^4.17.1, lodash@^4.17.2, lodash@^4.17.4, lodash@^4.2.0, lodash@^4.3.0, lodash@^4.6.1:
+"lodash@>=3.5 <5", lodash@^4.0.0, lodash@^4.11.1, lodash@^4.13.1, lodash@^4.14.0, lodash@^4.15.0, lodash@^4.17.0, lodash@^4.17.1, lodash@^4.17.2, lodash@^4.17.4, lodash@^4.2.0, lodash@^4.3.0, lodash@^4.6.1:
   version "4.17.4"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.4.tgz#78203a4d1c328ae1d86dca6460e369b57f4055ae"
 
@@ -9910,6 +9932,13 @@ webpack-hot-middleware@2.x:
     querystring "^0.2.0"
     strip-ansi "^3.0.0"
 
+webpack-manifest-plugin@^1.3.2:
+  version "1.3.2"
+  resolved "https://registry.yarnpkg.com/webpack-manifest-plugin/-/webpack-manifest-plugin-1.3.2.tgz#5ea8ee5756359ddc1d98814324fe43496349a7d4"
+  dependencies:
+    fs-extra "^0.30.0"
+    lodash ">=3.5 <5"
+
 webpack-sources@^1.0.1:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/webpack-sources/-/webpack-sources-1.1.0.tgz#a101ebae59d6507354d71d8013950a3a8b7a5a54"