fix: leave math functions for the browser when an argument is a runtime CSS var() - #4479
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📝 WalkthroughWalkthroughMathHelper now preserves supported runtime CSS ChangesRuntime CSS Math Handling
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Inline comments:
In `@packages/test-data/tests-unit/math-css-vars/math-css-vars.less`:
- Line 9: Add an empty line immediately before the “Concrete numeric arguments
still evaluate.” comment in the math CSS variables test fixture to satisfy
Stylelint, without changing the test content.
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packages/less/lib/less/functions/math-helper.jspackages/test-data/tests-unit/math-css-vars/math-css-vars.csspackages/test-data/tests-unit/math-css-vars/math-css-vars.less
…me CSS var() Signed-off-by: 林晨 (Leo Cheng) <leo-cheng@vip.qq.com>
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Fixed. |
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@Lfan-ke Less v5 will handle this more elegantly in general, but it's nice to get this finally patched for 4.x. Thank you. |
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Aug 1, 2026
* fix(issue#4339): limit whitespace check
* Fix issue #4339 by limiting the whitespace check for the deprecation
notice to not produce false positives.
* fix(issue#4339): correct deprecation notice
* Correct deprecation notice for issue #4339.
* fix:(issue#4397): container query variable names
* Fix for issue #4397 container query with variable names like
@container @foo () {}.
* feat(deprecation): add deprecation warnings for features removed in Less 5.x
New deprecation infrastructure with automatic repetition limiting (max 5 per type):
- deprecation.js: registry of deprecation IDs with descriptions
- Parser warn() accepts deprecation IDs for categorized warnings
- --quiet-deprecations: suppress only deprecation warnings (keeps other warnings)
New deprecation warnings for features being removed in 5.x:
- js-eval: inline JavaScript backtick expressions
- at-plugin: @plugin directive
Existing warnings now tagged with stable IDs:
- mixin-call-no-parens, mixin-call-whitespace, dot-slash-operator
- variable-in-unknown-value, property-in-unknown-value
CLI deprecation notices for: --js, --line-numbers, --math=always
* feat(benchmark): add historical benchmark suite with per-system result tracking
Results organized as:
results/latest/{system-id}.json - most recent per system
results/runs/{date}_{system-id}.json - historical archive (gitignored)
* fix(benchmark): don't path.resolve bare package names in benchmark-runner
path.resolve('less') turns the package name into an absolute filesystem
path, preventing Node's package resolution from finding npm-installed
versions. Only resolve relative paths starting with '.'.
* fix(benchmark): use coefficient of variation instead of range for variance_pct
variance_pct was computing (max-min)/avg which is range-over-mean.
Now uses stddev/avg (coefficient of variation) which is a proper
variability statistic.
* fix(benchmark): use timestamp instead of date for run filenames
Prevents same-day runs from overwriting each other in the runs/ archive.
* fix(cli): queue deprecation warnings until after arg parsing
Deprecation warnings from flags like --js, --line-numbers, and
--math=always were printed immediately during arg parsing, so
--quiet-deprecations only worked if it appeared before the deprecated
flag. Now all CLI deprecation messages are queued and flushed after
parsing completes, respecting --silent, --quiet, and
--quiet-deprecations regardless of flag order.
* Remove duplicate length check from expression.genCSS() (#4327)
Follows-up 53f84f02bad6e, which started the conditional
with a check for `i + 1 < this.value.length`, which is the same
as the parent block.
* Remove unused `parsers.entities.propertyCurly()` (#4271)
Follows-up a38f8a1eb7beed589d2fa734fcf411cf4461d231, which introduced
this as part of implementing property accessors. The method was not
used there, and hasn't been used elsewhere since then either.
Ref https://github.com/less/less.js/pull/3163.
* Remove redundant return from `parsers.blockRuleset()` (#4265)
* chore: replace deprecated String.prototype.substr() (#3702)
.substr() is deprecated so we replace it with .slice() which works similarily but isn't deprecated
Signed-off-by: Tobias Speicher <rootcommander@gmail.com>
* Handle the lack of the optional dependencies (#3791)
* Handle optional dependencies
* Handle optional dependency image-size
* remove phantom stuff (#3782)
* remove phantom stuff
* lint fix
* use deep clone
* fixed bug in import subpath module (#4236)
* fix(issue#4354): unknown at-rule expression commas (#4389)
* Fix issue less#4354 unknown at-rule expressions should not have commas in
a keyword list.
* Add some additional layer at-rule tests.
* chore: update README.md copyright (#4386)
* Update README.md copyright year.
* Fix no-prototype-builtins issues in Ruleset and ToCSSVisitor (#4404)
Co-authored-by: Timo Tijhof <krinkle@fastmail.com>
* chore: add test for number with underscore parsing (#4406)
In Less.js 2.6.0, parsing of dimensions changed so that `5_large`
is seen as one value, instead of as a list containing "5" and "_large".
In updating the Less.php port, we forgot to consider this change
because none of the Less.js 3.13 tests seem to cover this behavior.
Follows-up https://github.com/less/less.js/pull/2485.
This adds the test case from https://github.com/less/less.js/issues/2462,
as inpired by downstream https://gerrit.wikimedia.org/r/1197310.
Co-authored-by: Timo Tijhof <krinkle@fastmail.com>
* fix(#4331): exclude CSS at-rule keywords from declarationCall parsing (#4407)
* fix(#4331): exclude CSS at-rule keywords from declarationCall parsing
* fix(#4331): normalize spacing after CSS at-rule keywords in media queries
When `and`, `or`, `not`, or `only` keywords appear without a space
before `(` in media queries, ensure spacing is added in the output
to produce valid CSS.
* fix(#4358): resolve parent selectors in comma-separated pseudo-selector lists (#4408)
* refactor: code quality cleanup for container queries and related code (#4409)
* fix: correct import and error handling in style() function
- Fix incorrect import: `Anonymous` was imported from '../tree/variable'
instead of '../tree/anonymous' (worked by accident since Variable
was imported on the line above)
- Simplify switch/case with single case 0 to a plain if statement
- Add explanatory comment to the catch block documenting why it exists
(CSS pass-through for @container style() queries)
* refactor: remove dead boolean logic in evalRoot()
- Remove `allAmpersands` variable that was initialized to false and
never set to true, making it dead code
- Replace string-based ampersand detection (genCSS + regex) with
direct element value checks, avoiding unnecessary AST-to-string
conversion
- Simplify boolean conditions that referenced the dead variable
* fix: add missing parserInput.forget() in colorOperand
The colorOperand parser rule called parserInput.save() but only called
restore() on failure, missing the forget() call on the success path.
* refactor: QueryInParens eval() returns new node instead of mutating this
QueryInParens.eval() was mutating `this` directly instead of returning
a new node, violating the core Less.js tree pattern. It also used a
brittle queue pattern where deep copies were pushed to an `mvalues`
array during eval() and shifted off during genCSS().
Now eval() creates and returns a new QueryInParens with evaluated
children, and genCSS() reads directly from the node's properties.
The `copy-anything` import is removed from this file (still used
elsewhere in the codebase).
* refactor: extract mergeRules into shared utility to fix AtRule layering violation
AtRule.eval() was directly calling ToCSSVisitor.prototype._mergeRules,
which breaks the architectural boundary between tree nodes and visitors.
Extract the merge logic into a standalone utility (merge-rules.js) that
both AtRule.eval() and ToCSSVisitor can use without coupling.
* fix: remove Container copy-paste duplication and fix evalNested splice index bug
Container was overriding evalNested, permute, and bubbleSelectors with
identical copies of the methods already provided by NestableAtRulePrototype.
Remove the redundant overrides so Container properly inherits from the
shared prototype.
Also fix a bug in NestableAtRulePrototype.evalNested where
context.mediaBlocks.splice(i, 1) used `i` (the index into `path`) to
splice `mediaBlocks`. These are different arrays with different contents,
so the index was wrong. Use indexOf(this) to find the correct position.
* perf: optimize hot paths and fix benchmark infrastructure (#4410)
* fix(benchmark): fix division in benchmark files for v4 math defaults
Wrap bare divisions inside percentage() calls in extra parens so
benchmarks work with v4's default parens-division math mode. Add
--math option passthrough to benchmark-runner.js and pass
--math=always in run-historical.sh for consistent cross-version results.
* perf: remove unnecessary closures in hot paths
- Remove `extendVisitor` alias in findMatch, use `this` directly
- Replace IIFE closure for functionRegistry lookup in Ruleset.eval
with inline loop
~5% improvement on main benchmark (median 38.6ms → 37.1ms)
* perf: replace forEach/map closures with for loops in hot paths
- Selector.eval: replace map() closures with pre-allocated for loops
- Ruleset transformDeclaration: replace forEach with for loop
- extend-visitor visitRuleset: replace forEach with for loop, cache
extend and pathCount to reduce repeated property access
Combined with previous commit: ~8% improvement on 104KB benchmark
(median 38.6ms → 36.4ms)
* fix(benchmark): handle all v3.12+/v4.x build scenarios
- Use pnpm for v4.3+ (workspace: protocol)
- Fallback tsc installation when npm can't install locally
- Install runtime deps separately when npm fails due to
unpublished workspace packages (@less/test-import-module)
- Use last patch version of each minor release
- Skip v3.13.x (broken source: missing tree/util.js)
* bench: update benchmark results after hot-path optimizations
Median: 39.07ms → 34.32ms (~12% improvement)
Throughput: 2,495 KB/s → 2,828 KB/s
System: macbook-pro arm64
* bench: add historical benchmark results and track runs in git
- Add historical benchmark data (v3.5–v4.2) to results/runs/
- Update latest/ with all versions including v4.5.0-dev optimized results
- Format JSON with 2-space indentation
- Update .gitignore to track runs/ (historical records belong in git)
* bench: full historical benchmark run (v2.0–v4.5, 23 versions)
Apple M4 Pro, arm64, Node v18/v20/v24
Key findings:
- v2.4-v2.5 fastest era (~31ms median on 104KB file)
- v3.10-v3.12 massive regression (3-5x slower, 126-185ms)
- v4.0 recovered to ~40ms
- v4.2 fastest v4.x (35.4ms)
- v4.5.1 current master: 42.2ms
* bench: prune version list to significant performance changes
Reduced from 23 to 15 versions based on full benchmark data.
Dropped versions with <5% difference from their predecessor:
- v2.1 (broken), v2.5, v2.7 (plateau with v2.4/v2.6)
- v3.6–v3.9 (all within 1ms, flat ~41ms)
- v4.1 (identical to v4.0)
The full set can still be run with --versions flag.
* feat: migrate to native ESM with no build step (#4411)
* feat: migrate to native ESM with no build step
- Rename src/ to lib/ — source files are shipped directly, no compilation
- Add "type": "module" to package.json for native ESM support (Node 18+)
- Convert bin/lessc, test files, and build scripts from CJS to ESM
- Rename Gruntfile.js and .eslintrc.js to .cjs (must remain CommonJS)
- Add .js extensions to all relative import paths for ESM resolution
- Use createRequire() for optional dependency resolution (npm packages, JSON)
- Configure TypeScript for check-only mode (noEmit: true, allowJs: true)
- Update Rollup config to read from lib/ directly
- Update CI matrix to drop Node 16 (minimum Node 18+)
- Browser build is smaller: 500KB (was 509KB), minified 153KB (was 158KB)
- All 139 tests pass
* chore: fix trailing semicolons from linter
* chore: gitignore generated .css.map files in lib/
* fix(ci): restore lts/-3 to test matrix
* chore: stop tracking dist/ build artifacts
Generated browser bundles don't need to be in source control — they're
built during publish and included in the npm package via the files field.
Removes duplicate copies from both root dist/ and packages/less/dist/.
* fix(ci): use pnpm exec for playwright install
npx doesn't reliably find binaries with pnpm. Since playwright is
already a devDependency, use pnpm exec to run the installed version.
* fix(ci): use pnpm --filter for playwright, disable fail-fast
pnpm exec at workspace root can't find playwright binary since it's a
devDependency of the less package. Use --filter to run in that context.
Also disable fail-fast so all matrix jobs complete independently.
* fix(ci): move playwright to root devDependencies
Makes pnpm exec playwright work from workspace root in CI.
* fix: upgrade copy-anything to v3 for ESM compat, fix Windows test paths
copy-anything v2 lacks "type": "module", causing named import failures
on Node 18. v3 has proper ESM exports.
Revert testFolder to absolute path (matching original behavior) so debug
test path replacements match Less compiler output on Windows.
* chore: add CodeRabbit config to raise file review limit
* fix: add files field to package.json, remove postinstall from published package
Restricts npm package to only bin/, lib/, dist/, index.js, and README.md.
Previously shipped test files, Gruntfile, eslint config, etc.
Removes postinstall script (Playwright browser install) which only applies
in the monorepo dev environment and fails when installed from npm.
Verified: npm pack --dry-run shows 120 files (was 229), lessc CLI and
API both work from a clean tarball install.
* refactor: convert prototype-based tree nodes to ES6 classes (#4412)
* refactor: convert prototype-based tree nodes to ES6 classes
Convert all 30 tree node files from `Object.assign(new Node(), {...})`
prototype pattern to proper `class extends Node` syntax. This enables
TypeScript to understand the inheritance chain, reducing checkJs errors
from 2756 to 0.
- All tree nodes now use `class X extends Node` (or appropriate parent)
- Node.type converted from instance property to getter for clean override
- Factory functions in index.js updated to use `new` instead of
Object.create + apply (required for ES6 class compatibility)
- Benchmark script converted to ESM
- Added @types/node devDependency for checkJs support
- Enabled checkJs in tsconfig.json
- Added JSDoc types to node.js base class and several utility files
No behavioral changes - all 139 tests pass, benchmark performance
unchanged vs historical baselines (avg 36-39ms for 104KB).
* fix: @plugin deprecation says "replaced" not "removed"
* fix: use constructor params for AtRule selectors, path.resolve in benchmark
* fix: align @types/node with engines.node >=18 floor
* feat: JSDoc type annotations for all tree node files (#4413)
* feat: add JSDoc type annotations with @ts-check to all tree node files
Add proper JSDoc type annotations to all 44 files in lib/less/tree/,
enabling per-file TypeScript checking via @ts-check. No {*} or {any}
casts — all types are derived from reading the actual code.
Key changes:
- Shared types (EvalContext, CSSOutput, TreeVisitor, FileInfo, VisibilityInfo) defined in node.js
- Node.value typed as union: Node | Node[] | string | number | undefined
- Node.prototype.parse declared for parser-injected prototype property
- Constructor properties explicitly declared with proper types
- Inline casts used to narrow union types at usage sites
- Widened base class params where subclasses pass different types
Also adds typecheck to prepublishOnly and pre-commit hook to catch
regressions as more files are annotated toward global checkJs: true.
All 139 tests pass, zero TypeScript errors.
* fix: remove duplicate JSDoc type annotation in ruleset.js
* fix: pre-existing bug fixes in tree nodes (#4414)
* fix: preserve alpha 0 for fully transparent hex colors
#0000 and #00000000 parsed alpha as 0 which was treated as falsy by
the || operator, causing it to fall back to 1 (opaque). Use typeof
check instead so alpha 0 is preserved.
* fix: selector getElements callback `this` binding and forEach lint
- Capture `this._fileInfo` and `this.parse.imports` into locals before
the plain function callback in Selector.getElements(), where `this`
is undefined in strict mode (ES modules)
- Use explicit block in forEach to avoid implicit return of assignment
* fix: preserve full error context when rethrowing mixin call errors
The catch block in MixinCall.eval() only copied message and stack,
dropping type, extract, callLine, and other LessError fields. This
caused all mixin call errors to be reported as SyntaxError regardless
of their actual type (e.g. NameError). Use spread to preserve all
fields while still overriding index/filename to the call site.
* fix: guard functionRegistry.inherit() and fix atrule parenting
- Container and Media eval() now guard functionRegistry before calling
.inherit(), matching mixin-definition.js defensive pattern
- AtRule constructor: remove dead setParent(selectors) on orphaned local,
parent this.declarations and this.rules with null checks
* chore: release v4.6.0 (#4415)
* chore: prepare v4.6.0 release
- Bump version to 4.6.0 in all package.json files
- Add CHANGELOG entry for v4.6.0
- Update publish workflow: replace deprecated actions/create-release with
gh release create, attach dist files (less.js, less.min.js) as release
assets, bump contents permission to write
- Remove .github/** from paths-ignore (was preventing workflow updates)
- Update CONTRIBUTING.md with detailed release documentation
version: 4.6.0
* fix: publish workflow and provenance errors
- Add repository field to test-data package.json (fixes npm OIDC
provenance verification failure)
- Skip publish workflow on forks (only run on less/less.js)
- Remove duplicate require('fs') in bump-and-publish.js
- Add language specifier to markdown code block in CONTRIBUTING.md
* fix: handle existing releases for idempotent workflow re-runs
* fix: CJS compatibility, enriched npm README, ESM tests (#4417)
* docs: enrich npm README with usage examples and feature highlights
version: 4.6.0
* fix: update README and tests to show ESM + promise/await usage
The package is ESM-only ("type": "module"), so the README now correctly
shows `import less from 'less'` with `await` instead of CJS `require()`.
The ES6 test now verifies both promise/await and callback APIs.
version: 4.6.0
* fix: add CJS compatibility wrapper so require('less') works
Adds index.cjs as a one-line wrapper that re-exports the ESM default.
The exports field now has both import and require conditions.
Adds test-cjs.cjs to verify CJS consumption alongside the existing
ESM test.
version: 4.6.0
* fix: lazy Proxy CJS wrapper for Node 18+ compatibility
Node 22+ uses native require(esm). Node 18-20 uses a lazy Proxy with
dynamic import() — transparent because render()/parse() already return
promises. Tested with render, callback, and version property access.
* fix: include Node 20.19+ in native require(esm) path
* fix: add alt text to README images for accessibility
* fix: publish script skips stale version markers in squash merges (#4418)
* fix: skip stale version markers in squash merge commit messages
When a squash merge includes commit messages with `version: X.Y.Z`
from a previous release, the publish script would use that version
instead of auto-incrementing. Now checks if the requested version
already has a tag — if so, skips it and falls through to auto-increment.
* fix: simplify publish version logic — compare package.json vs NPM
Remove commit message version parsing entirely. The publish script now:
1. Checks EXPLICIT_VERSION env var (override)
2. If package.json > NPM version, uses package.json
3. Otherwise, bumps from latest NPM patch version
Updated CONTRIBUTING.md to reflect simplified workflow.
* chore: remove .claude directory and add to .gitignore (#4419)
* chore: remove .claude directory and add to .gitignore
* ci: skip publish for .gitignore and .claude changes
* fix: webpack browser build - use UMD dist/less.js, add CJS bundle (#4424)
* fix: webpack browser build - use UMD dist/less.js, add CJS bundle (#4423)
- Browser exports point to dist/less.js (UMD) instead of less-node
- Add CJS bundle (dist/less-node.cjs) for Node require() with module shim
- Remove dead index.js; index.cjs re-exports CJS bundle
- Add export tests: import-patterns, webpack-browser, test-cjs-suite
- CI and publish workflows run test:node (build + CJS + ESM tests)
* Beta publish script
* chore: clarify test:node runs ESM + CJS in workflow labels
* fix: normalize path separators in rollup plugin for Windows CI
The inlinePackageVersion plugin used forward-slash path check that
failed on Windows where rollup passes backslash-separated IDs,
leaving the require('../../package.json') unresolved at runtime.
* chore: bump version to 4.6.3 for release
* test: Add coverage for :is()/:matches()/:where() containing nested :has() selectors and comma-separated lists (#4422)
* Initial plan
* Initial plan
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* test: add test cases for :is()/:matches() containing :has() (fixes #4378)
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* test: add :where() and comma-separated list test cases for pseudo-selectors
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix: ensure npm publish is always backed by a GitHub tag, release, and version-bump commit (#4430)
* Initial plan
* fix: prevent npm publish when GitHub push fails, skip workflow on version bump commits
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* fix: skip version-bump commit entirely, push only the tag to bypass branch protection
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* fix: restore version-bump commit + push to master, add infinite-loop guard
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* fix: exclude .github and scripts from publish workflow trigger
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* feat: implement PR-based release flow for master
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* fix(less): upgrade make-dir to v4 to fix security vulnerability (#4426)
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix(issue#4356): parenthesis in media query (#4427)
* Fix issue #4356 issue with parenthesis in media query.
* Add tests for issue #4356.
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* feat: PR-based release flow for alpha; test suite proving all three release properties (#4431)
* Initial plan
* fix: correct release automation for master merges and publishing
- create-release-pr.yml: add set -euo pipefail; track whether a commit
was created; skip push + gh pr create when no version changes (no-op
safety - fixes the "no commits between head and base" failure).
- scripts/bump-and-publish.js: on master, use the version already in
package.json as-is (no auto-increment). Validate it is > NPM version.
Skip updateAllVersions/git-add/git-commit on master so the published
tag always points to the release PR merge commit on master, not to a
local detached commit. Alpha behavior is unchanged.
- Fix error message: on master say "Git tag was pushed" rather than
"Version bump commit and tag were pushed".
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* test: add release automation test suite (20 tests)
Proves the three components of the release flow work correctly:
- publish.yml if: conditions (6 scenarios)
- create-release-pr.yml if: conditions (4 scenarios)
- bump-and-publish.js master path: existing version, no commit, no push (4 tests)
- bump-and-publish.js alpha path: auto-increment, commit, alpha tag (4 tests)
- create-release-pr no-op safety: commit when needed, clean exit when not (2 tests)
Run with: node scripts/test-release-automation.js
or: npm run test:release (after pnpm install)
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* plan: implement PR-based release flow for alpha branch
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* feat: PR-based release flow for alpha branch (mirrors master)
- create-release-pr.yml: listen on alpha push; compute alpha version
increment (X.Y.Z-alpha.N → X.Y.Z-alpha.N+1); use branch-specific PR
title/base/branch naming; update loop guards for both flavours
- publish.yml: remove push:alpha trigger; add alpha to pull_request
branches; update if: condition for alpha release PR title+base
- bump-and-publish.js: remove auto-increment/commit/push for alpha;
add getNpmAlphaVersion(); alpha now validates and publishes like master
- test-release-automation.js: 34 tests covering new flows end-to-end
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* Fix `not` keyword silently ignored when used without parentheses in conditions (#4421)
* Initial plan
* Fix: not keyword now works without parentheses in guard conditions
Previously, `boolean(not false)` silently ignored the `not` keyword
while `boolean(not (false))` worked correctly.
The `negatedCondition` parser function consumed the `not` keyword but
only tried `parenthesisCondition`, which requires `(`. With no parens,
it returned undefined with `not` already consumed, causing silent skip.
Fix: fall back to `atomicCondition` when `parenthesisCondition` fails,
allowing both `not false` and `not (false)` to work consistently.
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* Restrict not-without-parens to simple values only (keywords/variables)
Complex conditions like `not 2 < 1` still require parentheses,
keeping alignment with CSS media query syntax. Only simple bare
values (keywords, variables, quoted strings) are allowed after
`not` without parens: `not false`, `not @var`.
Remove the `boolean(not 2 < 1)` test case that relied on the
broader atomicCondition fallback.
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* test: regression test for @container mixin parameter variable resolution (#4420)
* Initial plan
* Initial plan: add regression test for container mixin parameters issue
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* test: add regression test for container mixin parameters issue (#4420)
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix: update packageManager to pnpm@9.15.9 to match lockfileVersion 9.0 in pnpm-lock.yaml (#4432)
* Initial plan
* fix: trigger create-release-pr on any push to master/alpha, not just packages/**
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* fix: update packageManager to pnpm@9.15.9 to match lockfileVersion 9.0
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: matthew-dean <414752+matthew-dean@users.noreply.github.com>
* ci: fix Playwright chromium install hang on Node current/lts/* (#4445)
* ci: fix Playwright chromium install hang on Node current/lts/*
The `playwright install chromium` step was hanging for 1h+ on jobs using Node `current` and `lts/*` after the 163 MiB download completed (post-download extraction/setup blocked indefinitely).
Fixes:
- Add `timeout-minutes: 5` to fail fast instead of burning a runner for 6 hours
- Add `--with-deps` to install required system libraries (likely cause of the hang)
- Cache Playwright browser binaries via `actions/cache` using `PLAYWRIGHT_BROWSERS_PATH` pointed at `${{ github.workspace }}/.playwright-browsers` (cross-platform)
Older LTS jobs (lts/-1, lts/-2, lts/-3) were unaffected and completed fine.
* Refactor CI workflow for improved clarity
The `Install chromium` step was causing CI to hang indefinitely on Node current/lts/* (and timeout when we added a 5-min limit). Root cause: `test:node` only runs grunt node tests and has no browser dependency, so installing Chromium was never necessary in the first place.
Also drops the unused `env: PLAYWRIGHT_BROWSERS_PATH` and `actions/cache` step added in the previous commit.
* Fix browser export interop by routing bundlers to CJS-typed UMD artifact (#4444)
* Initial plan
* Fix browser export to CJS dist entry for bundler interop
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* Add Copilot review request job to CI workflow
Added a new job to request Copilot review for pull requests.
* fix: add continue-on-error to copilot-review CI job (#4448)
Updated CI workflow to include 'continue-on-error' for copilot-review job.
* chore: automate CHANGELOG generation in release workflow (#4447)
* chore: automate CHANGELOG generation in release workflow
Updated comments for clarity and consistency in the release PR workflow.
* fix: correct bash escaping in PR body template
Fix typo in push event and update release message format.
* chore: release v4.6.5 (#4436)
* chore: release v4.6.5
* docs: add CHANGELOG entries for v4.6.1 through v4.6.5
---------
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix: correct push event typo in create-release-pr workflow (pus → push:) (#4449)
* fix: use printf for PR body to avoid YAML indentation error in run block (#4450)
Removed redundant line from PR body in release workflow.
* docs: fix incorrect contributor attributions in v4.6.0 changelog (#4437)
Seven entries under v4.6.0 credited @nicolo-ribaudo for PRs authored by
other contributors. Updated each entry to match the actual PR author.
Fixes #4428
* chore: prevent dependency lifecycle scripts (#4440)
* chore: prevent dependency lifecycle scripts
* Prevent dependency lifecycle scripts during CI work.
* fix: partial revert for CI run
* Partial revert of CI run; keep only frozen lockfile so CI can
complete.
* fix: CI hang on chromium install
* Fix CI hang on chromium install; should not be needed for CI test
purposes.
* chore: re-add dependency script ignore for CI
* Re-add dependency script ignore for CI now that chromium hang is
resolved and CI can complete.
---------
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix(issue#4316): color calc inside from expression (#4434)
* Fix color calc() inside from expression parsing issues.
* Add tests for #4316.
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix: avoid crash on nested @supports with dumpLineNumbers (#4446)
A nested @supports (or @document) builds an implicit, non-root ruleset
that never gets a debugInfo attached during parsing. With dumpLineNumbers
enabled, genCSS tried to read lineNumber/fileName off that missing
debugInfo and threw a TypeError instead of producing output.
Skip emitting debug info when a node has none, the same way nodes without
a recorded line are already handled elsewhere.
* Preserve spacing for container feature functions (#4441)
* Preserve container feature function spacing
Signed-off-by: Puneet Dixit <236133619+puneetdixit200@users.noreply.github.com>
* Handle non-ASCII container names
---------
Signed-off-by: Puneet Dixit <236133619+puneetdixit200@users.noreply.github.com>
Co-authored-by: Puneet Dixit <236133619+puneetdixit200@users.noreply.github.com>
* chore: release v4.6.6 (#4451)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
* Fix failing "Request Copilot review" CI job (#4457)
* Initial plan
* Fix failing Request Copilot review CI job by handling 403 gracefully
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
* chore: release v4.6.7 (#4458)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
* feat: deprecate bare @variable in non-value at-rule positions (#4462)
* feat: deprecate bare @variable in non-value at-rule positions
Bare @var in at-rule preludes, names, and identifiers is deprecated in
favour of @{foo} interpolation; the bare form still resolves, so this is
a warning only (id: variable-in-at-rule-prelude, respects
--quiet-deprecations and the repetition cap).
Covered positions:
- @media / @container feature preludes
- @supports / @document / unknown & custom at-rule preludes
- @keyframes / @counter-style / @charset identifiers
- @layer names and lists
- @namespace prefix
@{foo} interpolation is now accepted in these positions as the migration
target (previously it errored in most of them). A bare @var in a nested
declaration value -- e.g. @supports (display: @v) or @media
(min-width: @v) -- is NOT deprecated: it is a declaration value and
stays valid, detected via paren-depth awareness so parsing and output
are unchanged.
Value-position parsing is otherwise untouched: @var works, @{var} is not
newly accepted in top-level declaration values.
Migrates existing fixtures to @{var} and adds a dedicated fixture
locking in backward-compatible resolution of the bare form.
* fix: also deprecate @@variable-variable prefix in @namespace
The @namespace prefix lookahead used `@[\w-]`, which misses an indirect
`@@ref` (variable-variable) reference — entities.variable() accepts
`@@name`, so `@namespace @@ref "..."` fell through to expression() and
resolved without the deprecation warning. Widen the lookahead to
`@@?[\w-]` so @@-prefixes hit the same warning path. Adds fixture
coverage.
* Fix #4460: parse comparison/range syntax in container style() queries (#4461)
* Fix #4460: parse comparison/range syntax in container style() queries
The mediaFeature lookahead regex only matched a bare identifier
before a comparison operator (=, >, <, >=, <=), so it failed
whenever the operand was a function call, e.g. var(--n) or
calc(6/2). Widened the regex to also match a single level of
balanced parens before the operator.
Added regression tests covering:
@container style(var(--n) = 3)
@container style(calc(6 / 2) = var(--n))
@container style(var(--size) > 1lh)
* Refactor parser.js for improved readability
---------
Co-authored-by: dweep <existing1.001@gmail>
* refactor: extract shared ESLint config and add lint scripts (#4459)
* refactor: extract shared ESLint config and add lint scripts
Addresses discussion #3787 by extracting shared ESLint rules to
config/eslint/base.cjs and adding lint/lint:fix npm scripts.
Changes:
- Created config/eslint/base.cjs with common ESLint rules
- Updated packages/less/.eslintrc.cjs to extend the shared config
- Added lint and lint:fix scripts to root package.json
The shared config maintains compatibility with both JS and TS
files. TypeScript-specific recommended rules are scoped to .ts
files only to avoid noise in legacy .js source files.
Verified: pnpm run lint passes with zero errors, 139/139 unit
tests pass (pre-commit hook failed only on unrelated port conflict).
* style: apply eslint --fix formatting
Auto-generated by 'pnpm run lint:fix' using the new shared config.
Touches only quote style and indentation; no logic changes.
- benchmark/benchmark-runner.js: indent
- build/rollup.js: quotes (backtick -> single)
- lib/less-node/environment.js: indent
- lib/less/tree/nested-at-rule.js: indent
* test(benchmark): add JSDoc for coverage
Addresses docstring coverage warning in PR #4459 by adding full
JSDoc to all functions in the benchmark-runner script.
* Replace image-size with probe-image-size (#4456)
* Replace image-size with probe-image-size
* validation
* Use loaded contents for image size probing
* Use loaded contents for image size probing
* chore: release v4.6.8 (#4463)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
* Follow-up to #4462: migrate remaining @var fixtures, DRY the prelude bare-@var scan, add warnings coverage (#4469)
* test: migrate remaining bare @variable at-rule fixtures to @{variable}
Follow-up to #4462, which deprecated bare @variable in non-value at-rule
positions and migrated most fixtures to @{variable} but left two feature
fixtures on the bare form:
- tests-unit/layer/layer.less @layer @layer-name
- tests-unit/import/import/import-reference.less @keyframes @keyframeName
Migrated to @{layer-name} / @{keyframeName} (byte-identical render).
Also repairs pnpm-lock.yaml: master had a dangling `minimatch: 3.1.2`
dependency edge with no package entry (bad-merge artifact), so
`pnpm install --frozen-lockfile` failed for every PR. Repinned to the
resolved 3.1.5 already present; no dependency version changes.
* test: assert deprecation/warning emission + suppress warnings in test output
less.js asserts errors via tests-error/*.txt but had no coverage that warnings
actually fire, so deprecation notices were unguarded (nothing would catch a
regression that silently stopped emitting one).
- Suppress warnings from normal test output (they are noise across the corpus);
set LESS_TEST_SHOW_WARNINGS=1 to see them.
- Add testWarnings() (run from index.js) which installs a capturing logger
listener and asserts each render-reachable warning fires: variable-in-at-rule-
prelude (incl. bar[@v] top-level -> warns and (x:@v) decl-value -> no warn),
js-eval, mixin-call-whitespace, mixin-call-no-parens, variable-in-unknown-value,
dot-slash-operator, complex-selector, extend-no-match, compress, at-plugin.
Documented gaps (not render-reachable): property-in-unknown-value (a $prop ref
resolves via the entity path before the permissive text scan), math-always and
dumpLineNumbers (registered in deprecation.js but never emitted via warn()).
* refactor(parser): fold at-rule prelude bare-@var detection into $parseUntil (DRY)
The at-rule-prelude deprecation detected a top-level bare @var two ways: the
permissiveValue entity loop (structural), plus a standalone hasTopLevelBareVariable()
that RE-SCANNED the same text $parseUntil had already walked, with its own hand-rolled
paren counter (and no string/comment handling).
Fold that second scan into $parseUntil's single pass: it already skips strings/comments/
escapes and tracks brackets, so add an opt-in `detectBareVar` that records the first bare
@var (not @{interp}) seen at PAREN depth 0 — [...]/{...} don't shield a reference, only a
declaration-value (...) does — exposed as `.bareVarIndex`. $parseUntil has a single caller
(permissiveValue), so the extra arg/property is contained. Delete hasTopLevelBareVariable.
Behaviour preserved (regression-guarded by testWarnings): @foo @bar -> 1, @a and @b -> 2,
bar[@v] -> 1 (bracket is top-level), (x:@v) -> 0 (decl value), and the mixed
(a:@x) y[@z] -> 1. Also drops the testWarnings 'variable-in-unknown-value' case: it only
fires for the inconsistent bracket edge (--x: bar[@bar]) while --x: @bar / 1px @bar /
foo(@bar) resolve silently, so asserting it would lock in an artifact (now documented).
* chore: release v4.7.0 (#4471)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
* Fix boolean() parsing for comparisons between inline condition expressions (#4472)
* Initial plan
* Fix boolean comparison of inline condition expressions
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
* fix(mixing): resolves issue #4234 (#4473)
* Fix mixin arity issue for mixins that provide a default value for
arguments early in the list that caused wrong number of arguments
error.
* chore: release v4.8.0 — deprecate legacy identifier forms and dynamic @charset (#4475)
* test: migrate remaining bare @variable at-rule fixtures to @{variable}
Follow-up to #4462, which deprecated bare @variable in non-value at-rule
positions and migrated most fixtures to @{variable} but left two feature
fixtures on the bare form:
- tests-unit/layer/layer.less @layer @layer-name
- tests-unit/import/import/import-reference.less @keyframes @keyframeName
Migrated to @{layer-name} / @{keyframeName} (byte-identical render).
Also repairs pnpm-lock.yaml: master had a dangling `minimatch: 3.1.2`
dependency edge with no package entry (bad-merge artifact), so
`pnpm install --frozen-lockfile` failed for every PR. Repinned to the
resolved 3.1.5 already present; no dependency version changes.
* test: assert deprecation/warning emission + suppress warnings in test output
less.js asserts errors via tests-error/*.txt but had no coverage that warnings
actually fire, so deprecation notices were unguarded (nothing would catch a
regression that silently stopped emitting one).
- Suppress warnings from normal test output (they are noise across the corpus);
set LESS_TEST_SHOW_WARNINGS=1 to see them.
- Add testWarnings() (run from index.js) which installs a capturing logger
listener and asserts each render-reachable warning fires: variable-in-at-rule-
prelude (incl. bar[@v] top-level -> warns and (x:@v) decl-value -> no warn),
js-eval, mixin-call-whitespace, mixin-call-no-parens, variable-in-unknown-value,
dot-slash-operator, complex-selector, extend-no-match, compress, at-plugin.
Documented gaps (not render-reachable): property-in-unknown-value (a $prop ref
resolves via the entity path before the permissive text scan), math-always and
dumpLineNumbers (registered in deprecation.js but never emitted via warn()).
* refactor(parser): fold at-rule prelude bare-@var detection into $parseUntil (DRY)
The at-rule-prelude deprecation detected a top-level bare @var two ways: the
permissiveValue entity loop (structural), plus a standalone hasTopLevelBareVariable()
that RE-SCANNED the same text $parseUntil had already walked, with its own hand-rolled
paren counter (and no string/comment handling).
Fold that second scan into $parseUntil's single pass: it already skips strings/comments/
escapes and tracks brackets, so add an opt-in `detectBareVar` that records the first bare
@var (not @{interp}) seen at PAREN depth 0 — [...]/{...} don't shield a reference, only a
declaration-value (...) does — exposed as `.bareVarIndex`. $parseUntil has a single caller
(permissiveValue), so the extra arg/property is contained. Delete hasTopLevelBareVariable.
Behaviour preserved (regression-guarded by testWarnings): @foo @bar -> 1, @a and @b -> 2,
bar[@v] -> 1 (bracket is top-level), (x:@v) -> 0 (decl value), and the mixed
(a:@x) y[@z] -> 1. Also drops the testWarnings 'variable-in-unknown-value' case: it only
fires for the inconsistent bracket edge (--x: bar[@bar]) while --x: @bar / 1px @bar /
foo(@bar) resolve silently, so asserting it would lock in an artifact (now documented).
* deprecate dash-only variable names
* deprecate dynamic charset interpolation
* chore: release v4.8.0
* chore: release v4.8.0 (#4474)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Matthew Dean <matthew-dean@users.noreply.github.com>
* fix: forwarding an unset variadic no longer overrides callee defaults (#4477)
Signed-off-by: 林晨 (Leo Cheng) <leo-cheng@vip.qq.com>
* fix: leave math functions for the browser when an argument is a runtime CSS var() (#4479)
Signed-off-by: 林晨 (Leo Cheng) <leo-cheng@vip.qq.com>
* fix(release): sync release version from PR title (#4483)
* fix(release): sync release version from PR title
* fix(release): harden title sync automation
* fix(release): harden title sync workflow
* fix(release): make changelog title sync idempotent
* fix(release): insert missing changelog heading on title sync
* fix(release): insert changelog heading without prior releases
* chore: release v4.8.1 (#4482)
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
* Less 5 alpha.1: Jess-powered compiler preview (#19)
* fix(issue#4339): limit whitespace check
* Fix issue #4339 by limiting the whitespace check for the deprecation
notice to not produce false positives.
* fix(issue#4339): correct deprecation notice
* Correct deprecation notice for issue #4339.
* Some updated tests for Less v5
* Update various acceptance tests for new parser
* Lots of v5 syntax tweaks
* Unit test updates for v5 - atrules
* v5 updates in test expectations
* Extend stylesheet changes
* fix:(issue#4397): container query variable names
* Fix for issue #4397 container query with variable names like
@container @foo () {}.
* Update unit tests to Less v5 engine
* Rebaseline test-data fixtures and move removed legacy JavaScript cases.
This updates expected outputs for current behavior and relocates removed inline-JavaScript and IE filter fixtures into explicit legacy/REMOVED folders to preserve historical references.
* Rebaseline import/media fixtures and skip alpha pre-commit test gate.
This updates import/media fixture expectations and moves the previous media v5 snapshot into legacy while keeping current output at media.css, and bypasses pre-commit verification on the alpha branch during broad migration work.
* test-data: update mixin fixture baselines with legacy snapshots
Capture accepted fixture output updates for mixin guard/default ordering and mixin output parity while preserving prior snapshots under legacy paths for traceability.
* Update parse-interpolation fixtures for selector capture semantics.
This removes the invalid quoted ampersand merge-template case from unit output expectations and moves it into tests-error/eval with an explicit invalid merge-template error fixture.
* Add nesting fixture variants (legacy, uncollapsed, styles.config)
* fix(test-data): update import-reference expected CSS for jess compat
Update expected output to match jess's collapseNesting behavior:
- Unwrap single-item :is() wrappers (.visible instead of :is(.visible))
- Simplify extend selectors (.visible + .visible instead of :is() form)
- Add .b { color: green; } from bare & { } (matches lessc output)
* fix(test-data): update extract-and-length expected CSS for @arguments semantics
BREAKING: @arguments no longer flattens Sequence arguments.
Passing .mixin(a b c d) to (...) gives @arguments length 1 (one Sequence),
not 4 (individual items). Previous expected output saved to legacy/.
* feat(benchmark): add historical benchmark suite for Less v2.0-v4.4
Comprehensive benchmark harness that tests every major/minor Less release
using git worktrees for isolation and fnm for Node version management.
- benchmark.less: enhanced with extend, guards, property merging, detached
rulesets, complex nesting, color functions, loops, and more
- benchmark-v3.less: v3.6+ features (if, boolean, property lookups)
- benchmark-v37.less: v3.7+ features (each with lists/maps)
- benchmark-v39.less: v3.9+ features (range for columns/spacing)
- benchmark-runner.js: portable runner with ESM interop for v4.x
- run-historical.sh: orchestrator with per-system result tracking
Results organized as:
results/latest/{system-id}.json - most recent per system
results/runs/{date}_{system-id}.json - historical archive
* feat(deprecation): add deprecation warnings for features removed in Less 5.x
New deprecation infrastructure with automatic repetition limiting (max 5 per type):
- deprecation.js: registry of deprecation IDs with descriptions
- Parser warn() accepts deprecation IDs for categorized warnings
- --quiet-deprecations: suppress only deprecation warnings (keeps other warnings)
New deprecation warnings for features being removed in 5.x:
- js-eval: inline JavaScript backtick expressions
- at-plugin: @plugin directive
Existing warnings now tagged with stable IDs:
- mixin-call-no-parens, mixin-call-whitespace, dot-slash-operator
- variable-in-unknown-value, property-in-unknown-value
CLI deprecation notices for: --js, --line-numbers, --math=always
* feat(benchmark): add historical benchmark suite with per-system result tracking
Results organized as:
results/latest/{system-id}.json - most recent per system
results/runs/{date}_{system-id}.json - historical archive (gitignored)
* fix(benchmark): don't path.resolve bare package names in benchmark-runner
path.resolve('less') turns the package name into an absolute filesystem
path, preventing Node's package resolution from finding npm-installed
versions. Only resolve relative paths starting with '.'.
* fix(benchmark): use coefficient of variation instead of range for variance_pct
variance_pct was computing (max-min)/avg which is range-over-mean.
Now uses stddev/avg (coefficient of variation) which is a proper
variability statistic.
* fix(benchmark): use timestamp instead of date for run filenames
Prevents same-day runs from overwriting each other in the runs/ archive.
* fix(cli): queue deprecation warnings until after arg parsing
Deprecation warnings from flags like --js, --line-numbers, and
--math=always were printed immediately during arg parsing, so
--quiet-deprecations only worked if it appeared before the deprecated
flag. Now all CLI deprecation messages are queued and flushed after
parsing completes, respecting --silent, --quiet, and
--quiet-deprecations regardless of flag order.
* Remove duplicate length check from expression.genCSS() (#4327)
Follows-up 53f84f02bad6e, which started the conditional
with a check for `i + 1 < this.value.length`, which is the same
as the parent block.
* Remove unused `parsers.entities.propertyCurly()` (#4271)
Follows-up a38f8a1eb7beed589d2fa734fcf411cf4461d231, which introduced
this as part of implementing property accessors. The method was not
used there, and hasn't been used elsewhere since then either.
Ref https://github.com/less/less.js/pull/3163.
* Remove redundant return from `parsers.blockRuleset()` (#4265)
* chore: replace deprecated String.prototype.substr() (#3702)
.substr() is deprecated so we replace it with .slice() which works similarily but isn't deprecated
Signed-off-by: Tobias Speicher <rootcommander@gmail.com>
* Handle the lack of the optional dependencies (#3791)
* Handle optional dependencies
* Handle optional dependency image-size
* remove phantom stuff (#3782)
* remove phantom stuff
* lint fix
* use deep clone
* fixed bug in import subpath module (#4236)
* fix(issue#4354): unknown at-rule expression commas (#4389)
* Fix issue less#4354 unknown at-rule expressions should not have commas in
a keyword list.
* Add some additional layer at-rule tests.
* chore: update README.md copyright (#4386)
* Update README.md copyright year.
* Fix no-prototype-builtins issues in Ruleset and ToCSSVisitor (#4404)
Co-authored-by: Timo Tijhof <krinkle@fastmail.com>
* chore: add test for number with underscore parsing (#4406)
In Less.js 2.6.0, parsing of dimensions changed so that `5_large`
is seen as one value, instead of as a list containing "5" and "_large".
In updating the Less.php port, we forgot to consider this change
because none of the Less.js 3.13 tests seem to cover this behavior.
Follows-up https://github.com/less/less.js/pull/2485.
This adds the test case from https://github.com/less/less.js/issues/2462,
as inpired by downstream https://gerrit.wikimedia.org/r/1197310.
Co-authored-by: Timo Tijhof <krinkle@fastmail.com>
* fix(#4331): exclude CSS at-rule keywords from declarationCall parsing (#4407)
* fix(#4331): exclude CSS at-rule keywords from declarationCall parsing
* fix(#4331): normalize spacing after CSS at-rule keywords in media queries
When `and`, `or`, `not`, or `only` keywords appear without a space
before `(` in media queries, ensure spacing is added in the output
to produce valid CSS.
* fix(#4358): resolve parent selectors in comma-separated pseudo-selector lists (#4408)
* refactor: code quality cleanup for container queries and related code (#4409)
* fix: correct import and error handling in style() function
- Fix incorrect import: `Anonymous` was imported from '../tree/variable'
instead of '../tree/anonymous' (worked by accident since Variable
was imported on the line above)
- Simplify switch/case with single case 0 to a plain if statement
- Add explanatory comment to the catch block documenting why it exists
(CSS pass-through for @container style() queries)
* refactor: remove dead boolean logic in evalRoot()
- Remove `allAmpersands` variable that was initialized to false and
never set to true, making it dead code
- Replace string-based ampersand detection (genCSS + regex) with
direct element value checks, avoiding unnecessary AST-to-string
conversion
- Simplify boolean conditions that referenced the dead variable
* fix: add missing parserInput.forget() in colorOperand
The colorOperand parser rule called parserInput.save() but only called
restore() on failure, missing the forget() call on the success path.
* refactor: QueryInParens eval() returns new node instead of mutating this
QueryInParens.eval() was mutating `this` directly instead of returning
a new node, violating the core Less.js tree pattern. It also used a
brittle queue pattern where deep copies were pushed to an `mvalues`
array during eval() and shifted off during genCSS().
Now eval() creates and returns a new QueryInParens with evaluated
children, and genCSS() reads directly from the node's properties.
The `copy-anything` import is removed from this file (still used
elsewhere in the codebase).
* refactor: extract mergeRules into shared utility to fix AtRule layering violation
AtRule.eval() was directly calling ToCSSVisitor.prototype._mergeRules,
which breaks the architectural boundary between tree nodes and visitors.
Extract the merge logic into a standalone utility (merge-rules.js) that
both AtRule.eval() and ToCSSVisitor can use without coupling.
* fix: remove Container copy-paste duplication and fix evalNested splice index bug
Container was overriding evalNested, permute, and bubbleSelectors with
identical copies of the methods already provided by NestableAtRulePrototype.
Remove the redundant overrides so Container properly inherits from the
shared prototype.
Also fix a bug in NestableAtRulePrototype.evalNested where
context.mediaBlocks.splice(i, 1) used `i` (the index into `path`) to
splice `mediaBlocks`. These are different arrays with different contents,
so the index was wrong. Use indexOf(this) to find the correct position.
* fix(benchmark): update scripts and results for v4.x compatibility
- Fix percentage() calls in benchmark .less files for parens-division
- Add --math=always passthrough to benchmark-runner.js
- Handle all v3.12+/v4.x build scenarios in run-historical.sh
(pnpm for workspace protocol, fallback tsc, separate runtime deps)
- Use last patch of each minor version in historical suite
- Update latest benchmark results (v2.0–v4.5.1)
* perf: optimize hot paths and fix benchmark infrastructure (#4410)
* fix(benchmark): fix division in benchmark files for v4 math defaults
Wrap bare divisions inside percentage() calls in extra parens so
benchmarks work with v4's default parens-division math mode. Add
--math option passthrough to benchmark-runner.js and pass
--math=always in run-historical.sh for consistent cross-version results.
* perf: remove unnecessary closures in hot paths
- Remove `extendVisitor` alias in findMatch, use `this` directly
- Replace IIFE closure for functionRegistry lookup in Ruleset.eval
with inline loop
~5% improvement on main benchmark (median 38.6ms → 37.1ms)
* perf: replace forEach/map closures with for loops in hot paths
- Selector.eval: replace map() closures with pre-allocated for loops
- Ruleset transformDeclaration: replace forEach with for loop
- extend-visitor visitRuleset: replace forEach with for loop, cache
extend and pathCount to reduce repeated property access
Combined with previous commit: ~8% improvement on 104KB benchmark
(median 38.6ms → 36.4ms)
* fix(benchmark): handle all v3.12+/v4.x build scenarios
- Use pnpm for v4.3+ (workspace: protocol)
- Fallback tsc installation when npm can't install locally
- Install runtime deps separately when npm fails due to
unpublished workspace packages (@less/test-import-module)
- Use last patch version of each minor release
- Skip v3.13.x (broken source: missing tree/util.js)
* bench: update benchmark results after hot-path optimizations
Median: 39.07ms → 34.32ms (~12% improvement)
Throughput: 2,495 KB/s → 2,828 KB/s
System: macbook-pro arm64
* bench: add historical benchmark results and track runs in git
- Add historical benchmark data (v3.5–v4.2) to results/runs/
- Update latest/ with all versions including v4.5.0-dev optimized results
- Format JSON with 2-space indentation
- Update .gitignore to track runs/ (historical records belong in git)
* bench: full historical benchmark run (v2.0–v4.5, 23 versions)
Apple M4 Pro, arm64, Node v18/v20/v24
Key findings:
- v2.4-v2.5 fastest era (~31ms median on 104KB file)
- v3.10-v3.12 massive regression (3-5x slower, 126-185ms)
- v4.0 recovered to ~40ms
- v4.2 fastest v4.x (35.4ms)
- v4.5.1 current master: 42.2ms
* bench: prune version list to significant performance changes
Reduced from 23 to 15 versions based on full benchmark data.
Dropped versions with <5% difference from their predecessor:
- v2.1 (broken), v2.5, v2.7 (plateau with v2.4/v2.6)
- v3.6–v3.9 (all within 1ms, flat ~41ms)
- v4.1 (identical to v4.0)
The full set can still be run with --versions flag.
* fix(benchmark): fix invalid CSS in benchmark.less and add Jess wrapper support
- Fix invalid CSS patterns in benchmark.less: hex-color selectors (#808080),
bare declarations in @media, :not(1), unquoted attr values, empty margin
- Add benchmark-runner.cjs for CJS compatibility with ESM package
- Add callback support to render() in lib/index.js alongside Promise return
* feat: migrate to native ESM with no build step (#4411)
* feat: migrate to native ESM with no build step
- Rename src/ to lib/ — source files are shipped directly, no compilation
- Add "type": "module" to package.json for native ESM support (Node 18+)
- Convert bin/lessc, test files, and build scripts from CJS to ESM
- Rename Gruntfile.js and .eslintrc.js to .cjs (must remain CommonJS)
- Add .js extensions to all relative import paths for ESM resolution
- Use createRequire() for optional dependency resolution (npm packages, JSON)
- Configure TypeScript for check-only mode (noEmit: true, allowJs: true)
- Update Rollup config to read from lib/ directly
- Update CI matrix to drop Node 16 (minimum Node 18+)
- Browser build is smaller: 500KB (was 509KB), minified 153KB (was 158KB)
- All 139 tests pass
* chore: fix trailing semicolons from linter
* chore: gitignore generated .css.map files in lib/
* fix(ci): restore lts/-3 to test matrix
* chore: stop tracking dist/ build artifacts
Generated browser bundles don't need to be in source control — they're
built during publish and included in the npm package via the files field.
Removes duplicate copies from both root dist/ and packages/less/dist/.
* fix(ci): use pnpm exec for playwright install
npx doesn't reliably find binaries with pnpm. Since playwright is
already a devDependency, use pnpm exec to run the installed version.
* fix(ci): use pnpm --filter for playwright, disable fail-fast
pnpm exec at workspace root can't find playwright binary since it's a
devDependency of the less package. Use --filter to run in that context.
Also disable fail-fast so all matrix jobs complete independently.
* fix(ci): move playwright to root devDependencies
Makes pnpm exec playwright work from workspace root in CI.
* fix: upgrade copy-anything to v3 for ESM compat, fix Windows test paths
copy-anything v2 lacks "type": "module", causing named import failures
on Node 18. v3 has proper ESM exports.
Revert testFolder to absolute path (matching original behavior) so debug
test path replacements match Less compiler output on Windows.
* chore: add CodeRabbit config to raise file review limit
* fix: add files field to package.json, remove postinstall from published package
Restricts npm package to only bin/, lib/, dist/, index.js, and README.md.
Previously shipped test files, Gruntfile, eslint config, etc.
Removes postinstall script (Playwright browser install) which only applies
in the monorepo dev environment and fails when installed from npm.
Verified: npm pack --dry-run shows 120 files (was 229), lessc CLI and
API both work from a clean tarball install.
* refactor: convert prototype-based tree nodes to ES6 classes (#4412)
* refactor: convert prototype-based tree nodes to ES6 classes
Convert all 30 tree node files from `Object.assign(new Node(), {...})`
prototype pattern to proper `class extends Node` syntax. This enables
TypeScript to understand the inheritance chain, reducing checkJs errors
from 2756 to 0.
- All tree nodes now use `class X extends Node` (or appropriate parent)
- Node.type converted from instance property to getter for clean override
- Factory functions in index.js updated to use `new` instead of
Object.create + apply (required for ES6 class compatibility)
- Benchmark script converted to ESM
- Added @types/node devDependency for checkJs support
- Enabled checkJs in tsconfig.json
- Added JSDoc types to node.js base class and several utility files
No behavioral changes - all 139 tests pass, benchmark performance
unchanged vs historical baselines (avg 36-39ms for 104KB).
* fix: @plugin deprecation says "replaced" not "removed"
* fix: use constructor params for AtRule selectors, path.resolve in benchmark
* fix: align @types/node with engines.node >=18 floor
* feat: JSDoc type annotations for all tree node files (#4413)
* feat: add JSDoc type annotations with @ts-check to all tree node files
Add proper JSDoc type annotations to all 44 files in lib/less/tree/,
enabling per-file TypeScript checking via @ts-check. No {*} or {any}
casts — all types are derived from reading the actual code.
Key changes:
- Shared types (EvalContext, CSSOutput, TreeVisitor, FileInfo, VisibilityInfo) defined in node.js
- Node.value typed as union: Node | Node[] | string | number | undefined
- Node.prototype.parse declared for parser-injected prototype property
- Constructor properties explicitly declared with proper types
- Inline casts used to narrow union types at usage sites
- Widened base class params where subclasses pass different types
Also adds typecheck to prepublishOnly and pre-commit hook to catch
regressions as more files are annotated toward global checkJs: true.
All 139 tests pass, zero TypeScript errors.
* fix: remove duplicate JSDoc type annotation in ruleset.js
* fix: pre-existing bug fixes in tree nodes (#4414)
* fix: preserve alpha 0 for fully transparent hex colors
#0000 and #00000000 parsed alpha as 0 which was treated as falsy by
the || operator, causing it to fall back to 1 (opaque). Use typeof
check instead so alpha 0 is preserved.
* fix: selector getElements callback `this` binding and forEach lint
- Capture `this._fileInfo` and `this.parse.imports` into locals before
the plain function callback in Selector.getElements(), where `this`
is undefined in strict mode (ES modules)
- Use explicit block in forEach to avoid implicit return of assignment
* fix: preserve full error context when rethrowing mixin call errors
The catch block in MixinCall.eval() only copied message and stack,
dropping type, extract, callLine, and other LessError fields. This
caused all mixin call errors to be reported as SyntaxError regardless
of their actual type (e.g. NameError). Use spread to preserve all
fields while still overriding index/filename to the call site.
* fix: guard functionRegistry.inherit() and fix atrule parenting
- Container and Media eval() now guard functionRegistry before calling
.inherit(), matching mixin-definition.js defensive pattern
- AtRule constructor: remove dead setParent(selectors) on orphaned local,
parent this.declarations and this.rules with null checks
* chore: release v4.6.0 (#4415)
* chore: prepare v4.6.0 release
- Bump version to 4.6.0 in all package.json files
- Add CHANGELOG entry for v4.6.0
- Update publish workflow: replace deprecated actions/create-release with
gh release create, attach dist files (less.js, less.min.js) as release
assets, bump contents permission to write
- Remove .github/** from paths-ignore (was preventing workflow updates)
- Update CONTRIBUTING.md with detailed release documentation
version: 4.6.0
* fix: publish workflow and provenance errors
- Add repository field to test-data package.json (fixes npm OIDC
provenance verification failure)
- Skip publish workflow on forks (only run on less/less.js)
- Remove duplicate require('fs') in bump-and-publish.js
- Add language specifier to markdown code block in CONTRIBUTING.md
* fix: handle existing releases for idempotent workflow re-runs
* fix: CJS compatibility…
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Math functions like
sin/cos/tan/atan2threwargument must be a numberwhen given a CSS custom property, since
var(--x)has no compile-time value:A
var()(or any unresolved CSS function) evaluates to aCallnode rather thana
Dimension. In that caseMathHelpernow returns nothing, so the call is leftintact for the browser to evaluate at runtime, matching how CSS handles it. Other
non-numeric arguments (colors, expressions) still error as before.
Numeric arguments are unaffected:
sin(30deg)still resolves to0.5. Added amath-css-varsfixture covering both the pass-through and the numeric paths;pnpm testpasses.Closes #4224
Summary by CodeRabbit
percentage) when given runtime values likevar(...)to no longer fail with incorrect numeric validation errors; expressions are now left for browser-side evaluation instead.calc()and updated expected error output forpercentage(var(...)).