Add short hash when serving bundles

package-lock.json

@@ -7650,6 +7650,12 @@
       "integrity": "sha512-6qE4B9deFBIa9YSpOc9O0Sgc43zTeVYbgDT5veRKSlB2+ZuHNoVVxA1L/ckMUayV9Ay9y7Z/SZCLcGteW9i7bg==",
       "dev": true
     },
+    "md5-file": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/md5-file/-/md5-file-4.0.0.tgz",
+      "integrity": "sha512-UC0qFwyAjn4YdPpKaDNw6gNxRf7Mcx7jC1UGCY4boCzgvU2Aoc1mOGzTtrjjLKhM5ivsnhoKpQVxKPp+1j1qwg==",
+      "dev": true
+    },
     "md5.js": {
       "version": "1.3.5",
       "resolved": "https://registry.npmjs.org/md5.js/-/md5.js-1.3.5.tgz",

package.json

@@ -104,6 +104,7 @@
     "file-loader": "^2.0.0",
     "har-validator": "^5.1.3",
     "husky": "^1.1.3",
+    "md5-file": "^4.0.0",
     "mini-css-extract-plugin": "^0.5.0",
     "mocha": "^5.2.0",
     "ndb": "^1.0.26",

server/render/renderFullPage.js

@@ -1,3 +1,10 @@
+const md5File = require('md5-file');
+const path = require('path');
+
+const bundlePath = path.resolve('./public/bundle/bundle.js');
+const bundleHash = md5File.sync(bundlePath);
+const shortBundleHash = bundleHash.substring(0,4);
+
 module.exports = (helmet, html, preloadedState) => {
   // take the html and preloadedState and return the full page
   return `
@@ -22,7 +29,7 @@ module.exports = (helmet, html, preloadedState) => {
             <script>
                 window.__PRELOADED_STATE__ = ${JSON.stringify(preloadedState).replace(/</g, '\\\u003c')}
             </script>
-            <script src="/bundle/bundle.js"></script>
+            <script src="/bundle/bundle.js?${shortBundleHash}"></script>
         </body>
     </html>
   `;