Merge pull request #2004 from daveajrussell/localhost-preview-rollout

Adds a localhost preview-as-default rollout service.

This will opt in all users on localhost by default, excluding those who have previously opted in to the preview, and then reverted to the old Browser.

Author: daveajrussell

src/browser/index.tsx

@@ -23,14 +23,16 @@ import ReactDOM from 'react-dom'
 import AppInit, { setupSentry } from './AppInit'
 import './init'
 import { navigateToPreview } from './modules/Stream/StartPreviewFrame'
+import { optedInByLocalhost } from 'browser-services/preview-optin-service'
 
 setupSentry()
+
 ;(async () => {
-  const doesPreferQuery = localStorage.getItem('prefersOldBrowser') === 'false'
+  const optedInToPreview = optedInByLocalhost()
   try {
     const response = await fetch('./preview/manifest.json')
     if (response.status === 200) {
-      if (doesPreferQuery) {
+      if (optedInToPreview) {
         navigateToPreview()
       } else {
         localStorage.setItem('previewAvailable', 'true')

src/browser/services/preview-optin-service.ts

@@ -0,0 +1,10 @@
+const notOptedOutOfPreview = (): boolean => {
+  const prefersOldBrowser = localStorage.getItem('prefersOldBrowser')
+  const doesPreferQuery = prefersOldBrowser === 'false'
+
+  return doesPreferQuery || prefersOldBrowser === null
+}
+
+export const optedInByLocalhost = (): boolean => {
+  return notOptedOutOfPreview() && window.location.hostname === 'localhost'
+}