feat: let a minify function format and place the extractComments banner by alexander-akait · Pull Request #752 · webpack/minimizer-webpack-plugin

alexander-akait · 2026-10-02T13:02:07Z

Summary

The extractComments banner is always written as /*! … */ at the top of the asset. That works for JS and CSS, but webpack's HTML minifier is going to extract license comments too, and in an HTML document that line is visible text placed before the doctype.

A minify function can now define two optional helpers, like getTypes or getStage:

formatBanner(banner) returns the comment to write, for example .
getBannerPosition() returns "start" (the default) or "end". With "end" the banner is appended with nothing in between, so the doctype stays first.

Without the helpers nothing changes. The output of webpack's HTML minimizer test case:

<!-- before -->
/*! For license information please see page.html.LICENSE.txt */
<!doctype html>…
<!-- after -->
<!doctype html>…<!-- For license information please see page.html.LICENSE.txt -->

What kind of change does this PR introduce?

feat

Did you add tests for your changes?

Yes, two cases in test/minify-option.test.js: one for formatBanner, one for getBannerPosition returning "end".

Does this PR introduce a breaking change?

No. Both helpers are optional.

If relevant, what needs to be documented once your changes are merged or what have you already documented?

Documented in the README under extractComments → banner. A changeset is included.

Use of AI

Written with Claude Code at the author's direction: the author chose the design (an HTML-style banner, placed at the end), and Claude implemented it, wrote the tests and ran the build, tests and lint.

🤖 Generated with Claude Code

https://claude.ai/code/session_01PodT59cXaxm4YzC9WBHr6P

Generated by Claude Code

Summary by CodeRabbit

New Features
- Extracted-comment banners can use a custom format, such as HTML comments, and appear at the start or end of minimized output.
- By default, banners retain the block-comment format and appear at the start. A shebang remains at the beginning when a banner is placed at the end.
- Errors while formatting a banner are reported for the affected asset, and processing stops.
- Different banner formatting helpers can affect chunk naming.
Documentation
- Updated banner guidance with examples of custom formatting and end-of-output placement, and notes on cache and chunk-hash behavior.

A `formatBanner` helper on the minify function replaces the `/*! … */` wrapper, so an HTML minimizer can write ``: a `/*!` line is text in a document, and before the doctype it switches to quirks mode.

A `getBannerPosition` helper returning `"end"` appends the banner instead of prepending it, so an HTML document keeps its doctype first.

changeset-bot · 2026-10-02T13:02:13Z

🦋 Changeset detected

Latest commit: b1b1034

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
minimizer-webpack-plugin	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

codecov · 2026-10-02T13:04:06Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.67%. Comparing base (7c7c64c) to head (b1b1034).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #752      +/-   ##
==========================================
+ Coverage   97.64%   97.67%   +0.02%     
==========================================
  Files           5        5              
  Lines        1697     1718      +21     
  Branches      652      664      +12     
==========================================
+ Hits         1657     1678      +21     
  Misses         39       39              
  Partials        1        1

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

The same lockfile change as #750, so npm audit passes in Lint.

coderabbitai · 2026-10-02T13:18:29Z

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: f23937a3-84ab-4cbb-a9cf-1fa6d0a9214b

📥 Commits

Reviewing files that changed from the base of the PR and between cc63bde and b1b1034.

📒 Files selected for processing (1)

README.md

🚧 Files skipped from review as they are similar to previous changes (1)

README.md

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 1 remain after this review.

Walkthrough

The plugin adds optional minimizer helpers to format extracted-comment banners and select their position. It uses the first declared helper for each option, with the default banner format and start position when helpers are not declared. A banner placed at the end follows the minimized source, and the plugin preserves a shebang at the start. Helper exceptions are reported against the asset. Minimizer identity includes the stringified banner helpers when they are declared.

Priority: ⬇️ Low

Merge Risk: ⚪ Minimal · up to b1b10

The banner documentation matches the implemented behavior. No issue identified in this review prevents merging after normal checks.

Security Architecture Review

Security architecture risk: 🔵 Low · up to cc63b

The hooks operate within trusted build configuration and existing asset-writing authority. The main concern is that stateful helpers can reuse outdated cached banners or skip a helper that would now fail. No new attacker-controlled execution boundary was established.

Retained concerns

Low · reliability · inferred: Banner-helper identity records source text rather than captured or bound state. If that state changes without a corresponding version change, otherwise identical builds can reuse stale banner output and bypass a helper that would now throw. This is a conditional cache and failure-containment gap, not a demonstrated authorization bypass.

Security review details

Security Blast Radius

inferred — The demonstrated exposure is selected assets and their cached outputs within a configured webpack compilation. The inspected hook path establishes neither a new tenant boundary nor a request-facing execution endpoint; external HTML-serving consumers remain outside the supplied scope.

Trust Boundaries and Controls

observed — Existing asset-name matching, minimizer filtering, and generated or already-processed asset checks remain upstream of hook selection. The new helpers reuse matched minimizers rather than deriving executable code from extracted comments.

Resilience and Maintainability Implications

inferred — Failure containment is sound for stable helper behavior on cache misses. Cached output bypasses helper invocation, so behavior changed through unversioned captured state can evade current error handling. The existing version hook provides a caller-controlled means to invalidate that output.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding optional helpers that format and place the extractComments banner.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 3…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

Commit to this branch
Create a new PR

Autopilot · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Autopilot is currently an internal CodeRabbit preview.

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

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

coderabbitai

Actionable comments posted: 3

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 01d009ca-9c8d-4a4e-afef-00b4194a742c

📥 Commits

Reviewing files that changed from the base of the PR and between 7c7c64c and 6419638.

⛔ Files ignored due to path filters (2)

package-lock.json is excluded by !**/package-lock.json
test/__snapshots__/minify-option.test.js.snap is excluded by !**/*.snap

📒 Files selected for processing (5)

.changeset/format-banner.md
README.md
src/index.js
test/minify-option.test.js
types/index.d.ts

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.

…ache on it An end banner now keeps the shebang it was split from, a formatBanner or getBannerPosition that throws becomes an error of that asset rather than rejecting processAssets, and a declared helper's source joins the cache and chunk-hash identity.

coderabbitai

Actionable comments posted: 1

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: ee7e621d-aa0d-475d-8730-31d83cd8e1b3

📥 Commits

Reviewing files that changed from the base of the PR and between 6419638 and cc63bde.

📒 Files selected for processing (2)

src/index.js
test/minify-option.test.js

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 2 remain after this review.

…ured state

alexander-akait added 2 commits October 2, 2026 13:01

feat: let a minify function format the extractComments banner

ee4b241

A `formatBanner` helper on the minify function replaces the `/*! … */` wrapper, so an HTML minimizer can write ``: a `/*!` line is text in a document, and before the doctype it switches to quirks mode.

feat: let a minify function put the extractComments banner at the end

3c2f491

A `getBannerPosition` helper returning `"end"` appends the banner instead of prepending it, so an HTML document keeps its doctype first.

chore(deps): bump fast-uri from 3.1.6 to 3.1.8

6419638

The same lockfile change as #750, so npm audit passes in Lint.

coderabbitai Bot reviewed Oct 2, 2026

View reviewed changes

Comment thread src/index.js

Comment thread src/index.js Outdated

Comment thread src/index.js Outdated

coderabbitai Bot reviewed Oct 2, 2026

View reviewed changes

Comment thread src/index.js

docs: say getMinimizerVersion must change with a banner helper's capt…

b1b1034

…ured state

alexander-akait merged commit 3ec4aca into main Oct 2, 2026
31 checks passed

alexander-akait deleted the feat/format-banner branch October 2, 2026 15:47

github-actions Bot mentioned this pull request Oct 2, 2026

chore(release): new release #751

Merged

alexander-akait mentioned this pull request Oct 2, 2026

feat(css, html): extract license comments, and shorten CSS gradients and shadows webpack/webpack#22408

Merged

Navigation Menu

Repository navigation

feat: let a minify function format and place the extractComments banner - #752

feat: let a minify function format and place the extractComments banner#752
alexander-akait merged 5 commits into
mainfrom
feat/format-banner

alexander-akait commented Oct 2, 2026 •

edited by coderabbitai Bot

Loading

Uh oh!

changeset-bot Bot commented Oct 2, 2026 •

edited

Loading

Uh oh!

codecov Bot commented Oct 2, 2026 •

edited

Loading

Uh oh!

coderabbitai Bot commented Oct 2, 2026 •

edited

Loading

Uh oh!

coderabbitai Bot left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

coderabbitai Bot left a comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

Conversation

alexander-akait commented Oct 2, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary by CodeRabbit

Uh oh!

changeset-bot Bot commented Oct 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🦋 Changeset detected

Uh oh!

codecov Bot commented Oct 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

coderabbitai Bot commented Oct 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Security Architecture Review

Uh oh!

coderabbitai Bot left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

coderabbitai Bot left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

alexander-akait commented Oct 2, 2026 •

edited by coderabbitai Bot

Loading

changeset-bot Bot commented Oct 2, 2026 •

edited

Loading

codecov Bot commented Oct 2, 2026 •

edited

Loading

coderabbitai Bot commented Oct 2, 2026 •

edited

Loading