Fix SSR tab hydration when using Strict Mode in development #2231
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React’s double rendering in strict mode in development makes SSR + hydration matching impossible without reaching into internals. This is unfortunate but the way react works. Production builds of React are unaffected by this but still require a consistent mechanism that works so in that case we use Symbols just like we do in SSR.
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This is going to break in React 19 fwiw. May I suggest |
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yeah we'll take a look. I figured this would break but we were supporting React 16/17/18 simultaneously. Now that Headless UI v2 is React 18+ only I can revisit this. |
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Here I've reworked the tab and panel counting mechanism to:
Symbol()when internals aren't available (only in SSR and prod builds where double rendering does not happen)The reason for this is that React’s double rendering in strict mode in development makes SSR + hydration impossible without reaching into internals. We reference the current fiber, walk up the tree of fibers, use the position of each fiber in its list of siblings to generate the key, and then use that as a "stable" reference. It is unfortunate that we have to do this at all but React doesn't give us the ability to do this using public API. The choices you have are basically: 1. No SSR at all; 2. SSR + hydration mismatches; 3. Use internals
Fixes #2220