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#JavaScript2 notes

All notes tagged “JavaScript”.

Notice on top of the Bilibili player saying the CDN was slow and playback switched to a backup node

Tech shareOct 25, 202614 min

Detecting CDN Failures in a Bilibili Extension and Falling Back to Backup Nodes

How the extension decides a CDN node is really broken: which errors to ignore, how to detect stalls from currentTime and the forward buffer, why it switches once quietly before asking you, and how it avoids bouncing between nodes. Also covers live streams.

繁體中文 / English

Cover: the Network panel domain changes from upos-hz-mirrorakam.akamaized.net to upos-sz-mirror08ct.bilivideo.com, above the four hook points: __playinfo__, the playurl API, .m4s segments and live streams

Tech shareOct 25, 202613 min

Rewriting Bilibili's Stream CDN on the Fly from a Chrome Extension's MAIN World

Bilibili's stream URLs arrive through SSR __playinfo__, the playurl API, segment requests and the live API. Using bilibili-cdn-switcher's code, this walks through hooking each path, what gets rewritten, and the traps: one-shot Response bodies, read-only XHR responseText, and speed tests that must bypass your own hooks.

繁體中文 / English