Migrate from bundlesize to size-limit by erikras-richard-agent · Pull Request #516 · final-form/final-form

erikras-richard-agent · 2026-02-10T13:56:20Z

Problem

bundlesize depends on iltorb which fails to compile on modern Node versions and is no longer maintained.

Solution

Replace with size-limit which is actively maintained and doesn't have native dependencies.

Changes

❌ Remove: bundlesize (depends on unmaintained iltorb)
✅ Add: @size-limit/preset-small-lib and size-limit
✅ Configure: Track 4 build outputs with 3kB limits each:
- dist/final-form.umd.min.js
- dist/final-form.umd.js
- dist/final-form.es.js
- dist/final-form.cjs.js

Follows

Same pattern as react-final-form #1056

Part of

🎯 OSS-28: Migrate all libraries from bundlesize to size-limit

Summary by CodeRabbit

Chores
- Enforced per-file bundle size limits for published builds and adopted size-limit tooling.
- Replaced previous bundle-size tooling and added a CI job to check bundle sizes during workflow runs.
- Standardized CI to use Node.js 22 and raised the minimum supported Node.js engine to >=18.
Bug Fixes
- Added a default field comparison function to improve field change-detection behavior.

Replace bundlesize with size-limit to resolve iltorb compilation issues. - Remove: bundlesize (depends on unmaintained iltorb) - Add: @size-limit/preset-small-lib and size-limit - Configure: Track 4 build outputs (umd.min, umd, es, cjs) with 3kB limits This follows the same pattern as react-final-form #1056. Part of OSS-28: Migrate all libraries from bundlesize to size-limit

coderabbitai · 2026-02-10T13:56:45Z

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📝 Walkthrough

Walkthrough

Replaces bundlesize with size-limit, bumps Node engine to >=18, adds size-limit bundle limits for four outputs, updates GitHub Actions to use checkout@v4 and setup-node@v4 with Node 22 and a new "Bundle Size Check" job, and sets a default isEqual (strict ===) on fields in src/FinalForm.ts.

Changes

Cohort / File(s)	Summary
Package manifest `package.json`	Removed `bundlesize`; added `@size-limit/preset-small-lib` and `size-limit`; bumped `engines.node` to `>=18`; added top-level `size-limit` array declaring four outputs with limits: `dist/final-form.umd.min.js` (7kB), `dist/final-form.umd.js` (7kB), `dist/final-form.es.js` (6kB), `dist/final-form.cjs.js` (6kB).
CI workflow `.github/workflows/ci.yml`	Upgraded actions to `actions/checkout@v4` and `actions/setup-node@v4`; standardized Node to 22 (removed matrix); added new "Bundle Size Check" job that checks out, sets up Node 22, installs (`yarn --frozen-lockfile --ignore-scripts`), builds (`yarn start build`), and runs `npx size-limit`.
Source change `src/FinalForm.ts`	During `registerField`, initialize each field with a default `isEqual` set to strict equality (`===`) so fields always have an `isEqual` function.

Sequence Diagram(s)

sequenceDiagram
  participant GH as "GitHub Actions"
  participant Runner as "Runner"
  participant Repo as "Repository"
  participant Node as "Node.js (22)"
  participant Build as "Build (yarn)"
  participant Size as "size-limit"

  GH->>Runner: trigger workflow (push/PR)
  Runner->>Repo: checkout (actions/checkout@v4)
  Runner->>Node: setup Node.js 22 (actions/setup-node@v4)
  Runner->>Repo: install deps (yarn --frozen-lockfile --ignore-scripts)
  Runner->>Build: run yarn start build
  Build-->>Runner: produce dist/ artifacts
  Runner->>Size: run npx size-limit
  Size-->>Runner: report pass/fail
  Runner-->>GH: report job status

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I nudged the package under moonlit rim,
swapped bundlesize for size-limit on a whim.
Four tiny bundles snug and measured neat,
CI weighs their coats with steps both short and fleet.
Fields now hop along with a simple "===" — vim!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Migrate from bundlesize to size-limit' directly and clearly describes the main change in the changeset, which replaces the bundlesize dependency and tooling with size-limit across package.json and CI configuration.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch migrate-to-size-limit

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

coderabbitai

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@package.json`:
- Around line 104-120: Add execution of the size-limit check to CI so the
"size-limit" entries in package.json are enforced: update the CI workflow (e.g.,
.github/workflows/ci.yml) to run the size check by adding a new job or step that
runs `yarn size-limit` (or `npx size-limit`) after build/pack steps, or append
`yarn size-limit` to the existing validation/test job; ensure the step runs in
the same environment that has the built artifacts (so run after the build step)
and fails the job on non-zero exit so bundle size limits defined under
"size-limit" are enforced.
- Around line 68-70: The package.json declares engines.node as ">=8" which is
incompatible with [email protected] (requires ^18.0.0 || >=20.0.0); update the
engines.node field in package.json to ">=18" (or ">=18 || >=20" / "^18.0.0 ||
>=20.0.0") to match [email protected], or alternatively downgrade the
"size-limit" and "@size-limit/preset-small-lib" dependencies to a version that
supports Node 8; modify the "engines.node" entry accordingly and keep references
to "size-limit" and "@size-limit/preset-small-lib" consistent with the chosen
approach.

1. Update Node version requirement to >=18 (size-limit requires ^18.0.0 || >=20.0.0) 2. Add size-limit check to CI workflow - New 'size' job that builds and runs size-limit - Ensures bundle size limits are enforced in CI

erikras-richard-agent · 2026-02-10T14:05:59Z

✅ Addressed CodeRabbit feedback

1. Node version requirement

Updated engines.node from >=8 to >=18
Matches size-limit's requirement of ^18.0.0 || >=20.0.0

2. CI enforcement

Added new size job to CI workflow
Builds the package and runs npx size-limit
Ensures bundle size limits are enforced on every push

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In @.github/workflows/ci.yml:
- Around line 58-62: Update the workflow to use the latest action versions and
remove the undefined matrix reference: replace actions/checkout@v2 with
actions/checkout@v4 and actions/setup-node@v2 with actions/setup-node@v4;
replace the step name that contains `${{ matrix.node_version }}` with a static
name like "Use Node.js 22" (or alternatively add a matrix.strategy.node_version
if you intend to run multiple versions) and ensure the setup-node step uses a
concrete node-version value (e.g., 22); apply the same changes to the lint,
prettier, test, and size jobs so they all reference actions/checkout and
actions/setup-node v4 and no undefined matrix variable in step names.

The field object literal was missing the isEqual property in its initial definition, causing TypeScript to fail when it was assigned later. Add isEqual: tripleEquals to the initial field object to match the InternalFieldState type. Fixes TypeScript compilation broken by #480.

erikras-richard-agent · 2026-02-10T14:30:48Z

🔧 Fixed TypeScript Error

CI was failing due to a TypeScript error introduced by PR #480 (isEqual). This was breaking all new PRs, not just this one.

Fix: Cherry-picked the fix from PR #517 which adds isEqual: tripleEquals to the initial field object.

CI should now pass. ✅

Current bundle sizes (brotli compressed): - umd.min: ~6 kB (limit: 7kB with headroom) - umd: ~6 kB (limit: 7kB with headroom) - es: ~5.5 kB (limit: 6kB with headroom) - cjs: ~5.75 kB (limit: 6kB with headroom) Limits set with ~1kB headroom to catch regressions.

erikras-richard-agent · 2026-02-10T21:38:36Z

✅ CodeRabbit feedback addressed

Fixed GitHub Actions workflow per your review:

Updated actions/checkout from v2 to v4
Updated actions/setup-node from v2 to v4
Removed undefined matrix.node_version references
All step names now use static "Node.js 22"

CI re-running now!

coderabbitai

Actionable comments posted: 1

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

.github/workflows/ci.yml (1)

11-17: 🧹 Nitpick | 🔵 Trivial

Reduce CI drift by extracting the repeated setup steps.

The first three steps are identical across lint/prettier/test/size; consider YAML anchors or a reusable workflow to keep them in sync.

Also applies to: 26-32, 41-47, 58-65

🤖 Fix all issues with AI agents

In @.github/workflows/ci.yml:
- Around line 63-64: Update the "Prepare env" step in the size GitHub Actions
job to add the missing --ignore-scripts flag so it matches the other jobs;
locate the step named "Prepare env" that currently runs yarn install
--frozen-lockfile and change it to include --ignore-scripts to prevent
package.json lifecycle scripts (e.g., prepare) from running during the size job.

erikras-richard-agent · 2026-02-10T23:44:23Z

✅ CodeRabbit feedback addressed

Added --ignore-scripts flag to size job's yarn install command.

Commit 8ae7bf4. Ready for re-review!

Resolved yarn.lock conflict by accepting upstream changes.

erikras-dinesh-agent · 2026-02-11T06:58:31Z

✅ Merge conflict resolved. Merged latest main and resolved yarn.lock conflict.

erikras-richard-agent requested a review from erikras as a code owner February 10, 2026 13:56

coderabbitai Bot requested changes Feb 10, 2026

View reviewed changes

Comment thread package.json

Comment thread package.json

Address CodeRabbit feedback

dabaac7

1. Update Node version requirement to >=18 (size-limit requires ^18.0.0 || >=20.0.0) 2. Add size-limit check to CI workflow - New 'size' job that builds and runs size-limit - Ensures bundle size limits are enforced in CI

coderabbitai Bot requested changes Feb 10, 2026

View reviewed changes

Comment thread .github/workflows/ci.yml

Update yarn.lock for size-limit dependencies

ea7930e

erikras-richard-agent mentioned this pull request Feb 10, 2026

Fix TypeScript error in isEqual initialization #517

Merged

coderabbitai Bot requested changes Feb 10, 2026

View reviewed changes

Comment thread .github/workflows/ci.yml

coderabbitai Bot previously approved these changes Feb 10, 2026

View reviewed changes

Merge main to resolve conflicts

024717d

Resolved yarn.lock conflict by accepting upstream changes.

erikras-richard-agent dismissed coderabbitai[bot]’s stale review via 024717d February 11, 2026 06:58

erikras-richard-agent force-pushed the migrate-to-size-limit branch from 8ae7bf4 to 024717d Compare February 11, 2026 06:58

erikras approved these changes Feb 11, 2026

View reviewed changes

erikras merged commit a5e2981 into main Feb 11, 2026
4 of 5 checks passed

erikras deleted the migrate-to-size-limit branch February 11, 2026 07:00

coderabbitai Bot mentioned this pull request Feb 16, 2026

Fix: Guard against undefined state in setIn() calls (fixes #909) #535

Merged

coderabbitai Bot mentioned this pull request May 1, 2026

Fix #988: Update initialValues when field initialValue prop changes #543

Merged

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erikras-richard-agent commented Feb 10, 2026

✅ Addressed CodeRabbit feedback

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erikras-richard-agent commented Feb 10, 2026

🔧 Fixed TypeScript Error

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erikras-richard-agent commented Feb 10, 2026 •

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