stream: deprecate legacy prependListener fallback#62435
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karan-lrn wants to merge 1 commit intonodejs:mainfrom
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stream: deprecate legacy prependListener fallback#62435karan-lrn wants to merge 1 commit intonodejs:mainfrom
karan-lrn wants to merge 1 commit intonodejs:mainfrom
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All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #62435 +/- ##
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Coverage 89.68% 89.69%
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Files 676 678 +2
Lines 206738 207206 +468
Branches 39594 39726 +132
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+ Hits 185414 185854 +440
+ Misses 13467 13447 -20
- Partials 7857 7905 +48
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cc @nodejs/streams @mcollina @ronag This PR removes the legacy Since Node.js v6 has been EOL for over 8 years, this cleanup removes ~15 lines of unnecessary code and the associated tests that explicitly tested the fallback behavior. |
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It would be better to deprecate this first
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Hey @mcollina The deprecation warning now fires when piping to an EventEmitter that lacks the Once this lands and goes through a few releases, we can remove the fallback code entirely. |
The prependListener method has been available on EventEmitter since Node.js v6.0.0 (April 2016). The internal fallback code that manually manipulates the _events object was intended for pre-v6 compatibility. This adds a runtime deprecation warning (DEP0205) when piping to an EventEmitter that lacks the prependListener method. The fallback behavior is preserved for now but will be removed in a future version. PR-URL: https://github.com/nodejs/node/pull/XXXXX Refs: https://github.com/nodejs/node/issues/XXXXX
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Commit Queue failed- Loading data for nodejs/node/pull/62435 β Done loading data for nodejs/node/pull/62435 ----------------------------------- PR info ------------------------------------ Title stream: deprecate legacy prependListener fallback (#62435) Author Karan Mangtani <karanmangtani5@gmail.com> (@karan-lrn) Branch karan-lrn:stream-remove-prependlistener-hack -> nodejs:main Labels stream, semver-major, needs-ci Commits 1 - stream: deprecate piping to emitters without prependListener Committers 1 - Karan Mangtani <karan.mangtani@lrn.com> PR-URL: https://github.com/nodejs/node/pull/62435 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Mattias Buelens <mattias@buelens.com> ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/62435 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Mattias Buelens <mattias@buelens.com> -------------------------------------------------------------------------------- βΉ This PR was created on Wed, 25 Mar 2026 20:25:37 GMT β Approvals: 3 β - Matteo Collina (@mcollina) (TSC): https://github.com/nodejs/node/pull/62435#pullrequestreview-4023940838 β - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/62435#pullrequestreview-4024660541 β - Mattias Buelens (@MattiasBuelens): https://github.com/nodejs/node/pull/62435#pullrequestreview-4025663529 β GitHub CI failed with status: FAILURE βΉ Last Full PR CI on 2026-03-28T22:58:04Z: https://ci.nodejs.org/job/node-test-pull-request/72172/ - Querying data for job/node-test-pull-request/72172/ β Build data downloaded - Querying failures of job/node-test-commit/86441/ β Data downloaded β 3 failure(s) on the last Jenkins CI run -------------------------------------------------------------------------------- β Aborted `git node land` session in /home/runner/work/node/node/.ncuhttps://github.com/nodejs/node/actions/runs/23706198878 |
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The prependListener method has been available on EventEmitter since Node.js v6.0.0 (April 2016). The fallback code that manipulated the internal _events object is no longer necessary.
This also removes tests that explicitly tested the fallback behavior.