demo · v149

Cache Key Probe

The inline-script cache is keyed by SHA-256 of the script source plus the network isolation key. Edit one byte of the script body and the key changes — the cache misses, the script must be parsed and compiled from scratch again. Watch the verdict flip.

SHA-256 of script body computing… · bytes:—
#cache key (first 24 chars)parse (ms)seen?verdict

Each "Load" runs the script inside a freshly-created blob iframe and times performance.now() from open to onload. The "verdict" column compares the SHA-256 of the script body across runs. Same key = should be cached (HIT). New key = recompile (MISS).

code

// Conceptual: each inline <script> gets cached by
//   SHA-256( script body ) + network isolation key

const enc = new TextEncoder();
const hashBuf = await crypto.subtle.digest('SHA-256', enc.encode(source));
const key = [...new Uint8Array(hashBuf)]
  .map(b => b.toString(16).padStart(2, '0')).join('');

The browser doesn't expose the cache lookup directly — but the timings make it observable. The first time a hash shows up, parse/compile runs in full. Subsequent runs with the same hash should be substantially faster on Chrome 149+ because the bytecode is restored from cache.

see also

implementation reference

Need the exact API surface, compatibility boundaries, errors, lifecycle, and source links? Read the matching gendn reference ↗