feat: use optional chaining in generated runtime code where supported#21186
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Add a RuntimeTemplate.optionalChaining helper that emits optional chaining when output.environment.optionalChaining is supported, and an equivalent && short-circuit otherwise. Use it in the load-script, auto-public-path and deferred-namespace runtime modules.
…sites Use RuntimeTemplate.optionalChaining in the chunk-loading (jsonp, import, readFile, require, importScripts), async-module, css-loading and module federation (remote/share/consume) runtime modules. Only convert property-access guards and method calls whose receiver is always object/array/null/undefined; keep `if (x)` guards where x can be a falsy non-nullish value (e.g. the `0` parent-callback sentinel), since optional chaining only short-circuits on null/undefined.
🦋 Changeset detectedLatest commit: 15c6491 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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This PR is packaged and the instant preview is available (793aae6). Install it locally:
npm i -D webpack@https://pkg.pr.new/webpack@793aae6
yarn add -D webpack@https://pkg.pr.new/webpack@793aae6
pnpm add -D webpack@https://pkg.pr.new/webpack@793aae6 |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #21186 +/- ##
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- Coverage 92.68% 92.68% -0.01%
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Files 587 588 +1
Lines 64011 64027 +16
Branches 17754 17760 +6
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+ Hits 59328 59341 +13
- Misses 4683 4686 +3
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Cover both the optional-chaining and && fallback output for property, call, method and computed access forms.
Merging this PR will improve performance by ×2.2
Performance Changes
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The optional-chaining output shrinks the publicPath runtime below 1 KiB, so verbose/detailed stats now report it in bytes.
Optional-chaining output reduces the entry asset size by a few bytes.
The test harness executes generated bundles in the same Node.js process, and Node < 14 cannot parse `?.`. Default output.environment.optionalChaining to the running Node's capability in the Config/Watch/Test/Hot templates so old Node gets the `&&` fallback while modern Node still exercises `?.`.
Those cases assert the target-derived output.environment, so forcing optionalChaining off on Node < 14 broke their snapshots. Keep the Node version guard for the other (execution-based) config cases.
It executes the federation bundle (with `promise?.then`) in-process via vm, which Node < 14 can't parse; gate optionalChaining on the running Node.
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Summary
output.environment.optionalChainingalready exists, but the generated runtime code almost never used it. This adds aRuntimeTemplate.optionalChaining(object, access)helper that emitsobj?.xwhen the target environment supports optional chaining and falls back to the existingobj && obj.xshort-circuit otherwise, then applies it across the runtime modules where it is safe (chunk loading for jsonp/import/readFile/require/importScripts, async modules, css loading, module federation remote/share/consume, load-script, auto-public-path, and deferred namespaces). No related issue.Only property-access guards and method calls whose receiver is always object/array/null/undefined are converted;
if (x)guards wherexcan be a falsy non-nullish value (e.g. the0parent-callback sentinel in the jsonp callback) are intentionally left as-is, because optional chaining only short-circuits onnull/undefined.What kind of change does this PR introduce?
feat
Did you add tests for your changes?
No new tests — the change only affects generated runtime code, which is executed end-to-end by the existing
HotTestCasesandConfigTestCasessuites. The&&fallback output is byte-identical to the previous code, and the?.output is exercised by the default modern-target runs; both were verified against baseline (no new failures).Does this PR introduce a breaking change?
No.
If relevant, what needs to be documented once your changes are merged or what have you already documented?
n/a
Use of AI
AI was used: Claude (Claude Code) helped locate candidate sites, write the
optionalChaininghelper and the edits, and run/compare the test suites. A test-driven review caught and reverted two unsafe conversions before submission. All changes were reviewed by me.Generated by Claude Code