All MDN pages flashing content, then redirecting to JSON about yari HOT 10 CLOSED

I have a similar (same?) issue, the page https://developer.mozilla.org/en-US is visible for a brief moment but then turns blank. The JS console showed something about updating and there was an error that sendBeacon didn't work. After I've switched on beacons by setting beacon.enabled to true in Firefox' about:config, it worked again. After then switching beacons off again, MDN continued to work. I have MDN plus, maybe that's relevant? Sorry, I don't have the exact error messages any more, but maybe that's useful nonetheless?

from yari.

Yep, that'll be it: we're trying to call sendBeacon when it's undefined. I thought Babel would ensure we conditionally call it for older browsers anyway, I had no idea it was possible to toggle it on/off through browser config.

PR incoming, but if you hit this again before we deploy, clear your auth-cookie to log off (or open MDN in a different container tab where you're not logged in) and the site will be usable.

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Resolved via #8089, which will land in about 6h.

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Funnily, it does partially render in the Response preview window

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Can't reproduce on my macOS Firefox 108.0.2 or Chrome 108.0.5359.124. But anyway it should be a platform issue

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Yeah, not seeing it on my PC. I'll try again later on the Mac to see if there is something that got cache poisoned, but it wasn't clearing with a hard refresh before

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went to look something up again on the mac again today and was still setting this with FF 109.

From the console

Content Security Policy: The page’s settings blocked the loading of a resource at data: (“media-src”).
TypeError: navigator.sendBeacon is not a function
    v hooks.ts:153
    React 3
    _ scheduler.production.min.js:13
    N scheduler.production.min.js:14
    4034 scheduler.production.min.js:14
    Webpack 12
react-dom.production.min.js:189:29
Uncaught TypeError: navigator.sendBeacon is not a function
    v hooks.ts:153
    React 3
    _ scheduler.production.min.js:13
    N scheduler.production.min.js:14
    4034 scheduler.production.min.js:14
    Webpack 12
hooks.ts:153:16
    v hooks.ts:153
    React 3
    _ scheduler.production.min.js:13
    N scheduler.production.min.js:14
    (Async: EventHandlerNonNull)
    4034 scheduler.production.min.js:14
    Webpack 12

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Interesting note, that when I disabled JavaScript on the page, everything renders correctly, but when JS is allowed, it appears that React is blowing again the content and falling on its face

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@LeoMcA I cannot reproduce this, but the sendBeacon call was introduced by your PR in #7940. Would you have any theory what's happening here?

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Thanks! :)

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