How MV3 Service Workers Made Me Use an Offscreen Document Just to Play a Goat Sound

So I built a Chrome extension that does one very stupid thing: it waits a random amount of time, then screams at you like a goat if you don't dismiss the notification fast enough. Simple idea. Should've been a simple build. It was not, because Manifest V3 said no. The plan was easy, in my head Here's what I thought I needed: chrome.alarms to fire at a random interval chrome.notifications to show a "you good?" popup If the user ignores it for 60 seconds, play a goat sound Step 3 is where things fell apart. Because in Manifest V3, your background script isn't a persistent background page anymore — it's a service worker. And service workers have the audio capabilities of a rock. No Audio() object. No Web Audio API. Nothing. You can't just do new Audio('goat.mp3').play() and call it a day, because there's no DOM for it to live in. I found this out the way everyone finds out things in MV3: by writing the obvious code, watching it silently fail, and then spending 20 minutes wondering if I'd misspelled "goat." Enter: the offscreen document Chrome's answer to "service workers can't do X" for a bunch of X's (audio playback included) is the offscreen document API . It's exactly what it sounds like — a hidden HTML page that exists purely so your extension has something with a DOM, so it can do DOM things. In my case, playing an mp3 of a goat losing its mind. The flow ends up looking like this: service worker (background.js) → creates an offscreen document if one doesn't exist → sends it a message: "play the sound" offscreen.html/offscreen.js → has an <audio> tag → actually plays the sound → closes itself when done It's a little bit like hiring a stunt double because the main actor (your service worker) isn't allowed near water. The offscreen document does the wet work, then goes home. Rough version of what that looks like in code: // background.js async function playGoatSound () { if ( ! ( await chrome . offscreen . hasDocument ())) { await chrome . offscreen . createDocument