Lighthouse: Flakiness with "Registers a service worker" audit

[ghost]

We have installed service worker, but lighthouse report saying service worker not installed.
Site URL : https://fuzecaresystem.com/

Please check screenshot:

[wardpeet]

can you tell us what version of lighthouse and what browser you are running it on?
Do you run it through lighthouse-cli or lighthouse browser extension?

I could not reproduce it.

[ghost]

Chrome Version 56.0.2924.87
lighthouse browser extension version 1.6.0

[wardpeet]

@AswathyNath do you have it every time or does it pass sometimes?

[ghost]

Yes, Sometimes this test pass with score 89/100

[wardpeet]

Looks like a duplicate of #1111
I will have a look into this

[stramel]

I'm also getting this issue.

Browser: Chrome 57.0.2987.110
Extension: Lighthouse 1.6.0

[wardpeet]

I have a fix ready but needs to be reviewed.
can you give us your url :)

[ghost]

Our url:
https://www.fuzecaresystem.com/

[sskhera]

Hi,
Is the issue resolved. We are also facing the same issue on our test environment. Want to make sure everything is fine before pushing the changes to Prod.

We are using lighthouse version 1.6.0

[ghost]

when switching network panel to offline
https://test.cilory.com/ showing offline TREX

[stramel]

I think I figured out why my site is showing no service worker.

I have jQuery (trying to get my company to get rid of it) and an adobe analytics script both fetch from CDNs.

Without them, the checks pass. With either script referencing the CDN, the audit fails both registering a service worker and returning a 200 when offline.

However, it does run offline when manually testing.

[ebidel]

@stramel can you provide the URL of that site?

[stramel]

@ebidel [retracted]

[ebidel]

@stramel I was able to look a bit at your site yesterday. It looked like the sw registration never happened because the function was returning before it gets to navigator.serviceWorker.register. You're hitting this line:

if (window.Polymer)
   return void console.error("Polymer already initialized!");

I also noticed waiting to register the sw until after window.onload. That could explain the timing differences with/without the CDN resources.

[stramel]

@ebidel Thanks for taking a look!

[ebidel]

I was also unable to repo on https://www.fuzecaresystem.com/ using LH's default throttling settings. However, the using Network Link Conditioner to throttle to DSL or lower does the trick!

You can also repo on WPT when running EM throttling. I just ran the easy setting: https://www.webpagetest.org/lighthouse.php?test=170415_YJ_ZMZ&run=2.

[stramel]

@ebidel Is loading the service worker after window.onload a bad thing? The PSK has it setup that way.

[ebidel]

No, not a bad thing. I expect many sites to do similar lazy loading techniques. For example, the new mobile.twitter.com PWA delays their registration even after page load.

We need to handle these cases better within LH :)

[ghost]

https://d-and-b.in/ showing serive worker not installed

[wardpeet]

@AswathyNath it's not yet available in the latest npm. It only works if you run from master but that might give other issues as we are heavily developing for a new release.