ep_002.md

Episode Two: Permission to Run

First on the API checklist in the migration guide:

Do you have host permissions in your permissions or optional_permissions arrays in manifest.json? Move host permissions into the host_permissions field.

Here's our V2 manifest, with old-school host permissions inside the permissions field, which would also hold other API permissions like storage, if we were using any:

{
  "version": "0.0.102",
  "name": "Baseline",
  "description": "Manifest V2 Baseline",
  "permissions": ["*://*/*"],
  "content_scripts": [
    {
      "js": ["js/content.js"],
      "matches": ["*://*/*"]
    }
  ],
  "manifest_version": 2
}

Here's our V3 manifest, with our host permissions request moved into the new host_permissions field:

{
  "version": "0.0.102",
  "name": "Test",
  "description": "Manifest V3 Test",
  "host_permissions": ["*://*/*"],
  "content_scripts": [
    {
      "js": ["js/content.js"],
      "matches": ["*://*/*"]
    }
  ],
  "manifest_version": 3
}

Here's our tiny content script for Manifest V2, saved as ep_002/v2/js/content.js:

console.log("Content script has loaded via Manifest V2.");

Here's our tiny content script for Manifest V3, saved as ep_002/v3/js/content.js:

console.log("Content script has loaded via Manifest V3.");

Load by dragging ep_002/v2 and ep_002/v3 into chrome://extensions. Both of these will run in Chrome Canary, so you don't (yet) need to be running two browsers side-by-side.

Check for errors (yes, the Manifest V3 version will still squawk about that 3 in manifest_version not being supported).

Open a new page, inspect, go to your Console tab, and see if you see these two lines:

Content script has loaded via Manifest V2.
Content script has loaded via Manifest V3.

Status

Seems good.