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Comment by mindcrash | Hacker News Reader

So basically the Mozilla exec is saying that the Chrome implementation of the Web Components W3 standard is a lot faster than Mozilla's implementation.

Because that is what YouTube's frontend is currently running under the hood: Web Components and Shadow DOM. Both W3 standards. No magic at all.

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FTA: "YouTube's Polymer redesign relies on the deprecated Shadow DOM v0 API only implemented in Chrome". Shadow DOM v0 never was a standard, merely a proposal in a draft.

Both Polymer v2 (previous version) and Polymer v3 (current version) are based on Shadow DOM v1, as can be seen in the docs (https://www.polymer-project.org/3.0/docs/devguide/shadow-dom, https://www.polymer-project.org/2.0/docs/devguide/feature-ov...) so this statement is VERY strange.

Although it's true that only Safari and Chrome (through WebKit and Blink) currently have the best support for Web Components, and polyfills are required for everything else due to flaky support.

Google even mentions this in the Polymer README:

"Web Components are now implemented natively on Safari and Chrome (~70% of installed browsers), and run well on Firefox, Edge, and IE11 using polyfills. Read more below."

Source: https://github.com/Polymer/polymer

Well, if I check the source of the desktop_polymer.js on Youtube I see v0 API calls in it, and not their v1 equivalents. (e.g. createShadowRoot vs attachShadow). I might be missing something, since I obviously don't understand how all of that works, but it seems supportive at least?

Youtube is using Polymer v1 as far as I can tell.

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