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Fix erroneous diffing w/ growing list #4975

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Merged
JoviDeCroock merged 2 commits into from
Dec 16, 2025
Merged

Fix erroneous diffing w/ growing list #4975

JoviDeCroock merged 2 commits into from
Dec 16, 2025
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@JoviDeCroock JoviDeCroock commented Dec 16, 2025 •
edited
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Resolves #4973

When we diff a list of children and in the new list an item gets added
we will diff the newly added item against the oldVNode of its previous sibling
due to the global nature of oldVNode

Test failure without the children diff:

Screenshot 2025-12-16 at 20 21 41

@JoviDeCroock
Fix cause where oldVNode can carry over
b109450 
When we diff a list of children and in the new list an item gets added
we will diff the newly added item against the oldVNode of its previous sibling
due to the global nature of oldVNode
@github-actions
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github-actions bot commented Dec 16, 2025 •
edited
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📊 Tachometer Benchmark Results

Summary

duration

  • create10k: unsure 🔍 -0% - +1% (-3.51ms - +6.78ms)
    preact-local vs preact-main
  • filter-list: unsure 🔍 -1% - +0% (-0.09ms - +0.03ms)
    preact-local vs preact-main
  • hydrate1k: unsure 🔍 -0% - +2% (-0.22ms - +1.00ms)
    preact-local vs preact-main
  • many-updates: unsure 🔍 -3% - +1% (-0.42ms - +0.15ms)
    preact-local vs preact-main
  • replace1k: unsure 🔍 -2% - +1% (-1.01ms - +0.56ms)
    preact-local vs preact-main
  • text-update: unsure 🔍 -8% - +3% (-0.17ms - +0.07ms)
    preact-local vs preact-main
  • todo: unsure 🔍 -2% - +0% (-0.58ms - +0.16ms)
    preact-local vs preact-main
  • update10th1k: unsure 🔍 -5% - +4% (-1.49ms - +1.33ms)
    preact-local vs preact-main

usedJSHeapSize

  • create10k: unsure 🔍 +0% - +0% (+0.00ms - +0.00ms)
    preact-local vs preact-main
  • filter-list: unsure 🔍 -0% - +0% (-0.00ms - +0.00ms)
    preact-local vs preact-main
  • hydrate1k: unsure 🔍 -10% - +3% (-0.62ms - +0.18ms)
    preact-local vs preact-main
  • many-updates: unsure 🔍 -0% - +0% (-0.00ms - +0.00ms)
    preact-local vs preact-main
  • replace1k: unsure 🔍 -0% - +0% (-0.00ms - +0.00ms)
    preact-local vs preact-main
  • text-update: unsure 🔍 -2% - +3% (-0.02ms - +0.03ms)
    preact-local vs preact-main
  • todo: unsure 🔍 -0% - -0% (-0.01ms - -0.00ms)
    preact-local vs preact-main
  • update10th1k: unsure 🔍 -0% - +0% (-0.00ms - +0.01ms)
    preact-local vs preact-main

Results

create10k

duration

VersionAvg timevs preact-localvs preact-main
preact-local884.31ms - 892.20ms-unsure 🔍
-0% - +1%
-3.51ms - +6.78ms
preact-main883.31ms - 889.92msunsure 🔍
-1% - +0%
-6.78ms - +3.51ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local19.19ms - 19.19ms-unsure 🔍
+0% - +0%
+0.00ms - +0.00ms
preact-main19.19ms - 19.19msunsure 🔍
-0% - -0%
-0.00ms - -0.00ms		-
filter-list

duration

VersionAvg timevs preact-localvs preact-main
preact-local16.49ms - 16.59ms-unsure 🔍
-1% - +0%
-0.09ms - +0.03ms
preact-main16.53ms - 16.61msunsure 🔍
-0% - +1%
-0.03ms - +0.09ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local1.56ms - 1.56ms-unsure 🔍
-0% - +0%
-0.00ms - +0.00ms
preact-main1.55ms - 1.56msunsure 🔍
-0% - +0%
-0.00ms - +0.00ms		-
hydrate1k
  • Browser: chrome-headless
  • Sample size: 100
  • Built by: CI #5249

  • Commit: ce55fc5

duration

VersionAvg timevs preact-localvs preact-main
preact-local59.12ms - 59.96ms-unsure 🔍
-0% - +2%
-0.22ms - +1.00ms
preact-main58.70ms - 59.59msunsure 🔍
-2% - +0%
-1.00ms - +0.22ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local5.78ms - 6.36ms-unsure 🔍
-10% - +3%
-0.62ms - +0.18ms
preact-main6.02ms - 6.57msunsure 🔍
-3% - +10%
-0.18ms - +0.62ms		-
many-updates

duration

VersionAvg timevs preact-localvs preact-main
preact-local16.41ms - 16.55ms-unsure 🔍
-3% - +1%
-0.42ms - +0.15ms
preact-main16.34ms - 16.89msunsure 🔍
-1% - +3%
-0.15ms - +0.42ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local3.72ms - 3.72ms-unsure 🔍
-0% - +0%
-0.00ms - +0.00ms
preact-main3.72ms - 3.72msunsure 🔍
-0% - +0%
-0.00ms - +0.00ms		-
replace1k
  • Browser: chrome-headless
  • Sample size: 100
  • Built by: CI #5249

  • Commit: ce55fc5

duration

VersionAvg timevs preact-localvs preact-main
preact-local56.35ms - 57.54ms-unsure 🔍
-2% - +1%
-1.01ms - +0.56ms
preact-main56.65ms - 57.68msunsure 🔍
-1% - +2%
-0.56ms - +1.01ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local3.00ms - 3.00ms-unsure 🔍
-0% - +0%
-0.00ms - +0.00ms
preact-main3.00ms - 3.00msunsure 🔍
-0% - +0%
-0.00ms - +0.00ms		-

run-warmup-0

VersionAvg timevs preact-localvs preact-main
preact-local25.96ms - 26.75ms-unsure 🔍
-4% - +0%
-0.98ms - +0.12ms
preact-main26.39ms - 27.18msunsure 🔍
-0% - +4%
-0.12ms - +0.98ms		-

run-warmup-1

VersionAvg timevs preact-localvs preact-main
preact-local31.43ms - 32.62ms-unsure 🔍
-3% - +3%
-0.91ms - +0.92ms
preact-main31.33ms - 32.71msunsure 🔍
-3% - +3%
-0.92ms - +0.91ms		-

run-warmup-2

VersionAvg timevs preact-localvs preact-main
preact-local31.64ms - 32.80ms-unsure 🔍
-2% - +3%
-0.58ms - +1.11ms
preact-main31.34ms - 32.57msunsure 🔍
-3% - +2%
-1.11ms - +0.58ms		-

run-warmup-3

VersionAvg timevs preact-localvs preact-main
preact-local25.36ms - 25.71ms-unsure 🔍
-1% - +1%
-0.25ms - +0.30ms
preact-main25.31ms - 25.72msunsure 🔍
-1% - +1%
-0.30ms - +0.25ms		-

run-warmup-4

VersionAvg timevs preact-localvs preact-main
preact-local23.44ms - 24.62ms-faster ✔
3% - 9%
0.68ms - 2.45ms
preact-main24.94ms - 26.25msslower ❌
3% - 10%
0.68ms - 2.45ms		-

run-final

VersionAvg timevs preact-localvs preact-main
preact-local21.27ms - 21.80ms-unsure 🔍
-2% - +1%
-0.45ms - +0.28ms
preact-main21.36ms - 21.88msunsure 🔍
-1% - +2%
-0.28ms - +0.45ms		-
text-update
  • Browser: chrome-headless
  • Sample size: 230
  • Built by: CI #5249

  • Commit: ce55fc5

duration

VersionAvg timevs preact-localvs preact-main
preact-local1.93ms - 2.09ms-unsure 🔍
-8% - +3%
-0.17ms - +0.07ms
preact-main1.98ms - 2.15msunsure 🔍
-3% - +9%
-0.07ms - +0.17ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local1.00ms - 1.04ms-unsure 🔍
-2% - +3%
-0.02ms - +0.03ms
preact-main0.99ms - 1.03msunsure 🔍
-3% - +2%
-0.03ms - +0.02ms		-
todo

duration

VersionAvg timevs preact-localvs preact-main
preact-local32.56ms - 32.97ms-unsure 🔍
-2% - +0%
-0.58ms - +0.16ms
preact-main32.67ms - 33.28msunsure 🔍
-0% - +2%
-0.16ms - +0.58ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local1.26ms - 1.26ms-unsure 🔍
-0% - -0%
-0.01ms - -0.00ms
preact-main1.26ms - 1.27msunsure 🔍
+0% - +0%
+0.00ms - +0.01ms		-
update10th1k

duration

VersionAvg timevs preact-localvs preact-main
preact-local32.01ms - 34.03ms-unsure 🔍
-5% - +4%
-1.49ms - +1.33ms
preact-main32.12ms - 34.09msunsure 🔍
-4% - +5%
-1.33ms - +1.49ms		-

usedJSHeapSize

VersionAvg timevs preact-localvs preact-main
preact-local2.97ms - 2.99ms-unsure 🔍
-0% - +0%
-0.00ms - +0.01ms
preact-main2.97ms - 2.98msunsure 🔍
-0% - +0%
-0.01ms - +0.00ms		-

tachometer-reporter-action v2 for CI

@JoviDeCroock JoviDeCroock changed the title Fix erroneos diffing Fix erroneous diffing w/ growing list Dec 16, 2025
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github-actions bot commented Dec 16, 2025 •
edited
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Size Change: +11 B (+0.01%)

Total Size: 79.2 kB

Filename Size Change
dist/preact.js 4.77 kB +2 B (+0.04%)
dist/preact.min.js 4.8 kB +1 B (+0.02%)
dist/preact.min.module.js 4.8 kB +2 B (+0.04%)
dist/preact.min.umd.js 4.82 kB +1 B (+0.02%)
dist/preact.mjs 4.79 kB +2 B (+0.04%)
dist/preact.module.js 4.79 kB +2 B (+0.04%)
dist/preact.umd.js 4.83 kB +1 B (+0.02%)
ℹ️ View Unchanged
Filename Size
compat/dist/compat.js 4.17 kB
compat/dist/compat.mjs 4.1 kB
compat/dist/compat.module.js 4.1 kB
compat/dist/compat.umd.js 4.24 kB
debug/dist/debug.js 3.85 kB
debug/dist/debug.mjs 3.85 kB
debug/dist/debug.module.js 3.85 kB
debug/dist/debug.umd.js 3.93 kB
devtools/dist/devtools.js 260 B
devtools/dist/devtools.mjs 273 B
devtools/dist/devtools.module.js 273 B
devtools/dist/devtools.umd.js 346 B
hooks/dist/hooks.js 1.54 kB
hooks/dist/hooks.mjs 1.57 kB
hooks/dist/hooks.module.js 1.57 kB
hooks/dist/hooks.umd.js 1.61 kB
jsx-runtime/dist/jsxRuntime.js 1.01 kB
jsx-runtime/dist/jsxRuntime.mjs 985 B
jsx-runtime/dist/jsxRuntime.module.js 985 B
jsx-runtime/dist/jsxRuntime.umd.js 1.08 kB
test-utils/dist/testUtils.js 473 B
test-utils/dist/testUtils.mjs 477 B
test-utils/dist/testUtils.module.js 477 B
test-utils/dist/testUtils.umd.js 555 B

compressed-size-action

@JoviDeCroock JoviDeCroock mentioned this pull request Dec 16, 2025
Merged
@JoviDeCroock JoviDeCroock merged commit f7693b7 into v10.x Dec 16, 2025
12 checks passed
@JoviDeCroock JoviDeCroock deleted the fix-erroneos-diffing branch December 16, 2025 19:26
@JoviDeCroock JoviDeCroock mentioned this pull request Dec 17, 2025
Merged
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@rschristian rschristian rschristian approved these changes

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