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node-fallbacks: keep emit("error") arguments and throw ERR_UNHANDLED_ERROR in the events and domain polyfills - #48591
In a browser bundle, emit("error") gives "error" and errorMonitor listeners a made-up Error("Unhandled error."). With no listener, emit("error", "str") throws the string itself.
With no "error" listener it throws an Error as it is. Each other value goes in the context of an Error with codeERR_UNHANDLED_ERROR. The message names a primitive: Unhandled error. ('str').
The domain polyfill replaces a falsy "error" value of an added emitter with that error, as Node does.
Verified: test/bundler/bundler_browser.test.ts (3 new cases, 2 fail on bun 1.4.3). Self-reviewed: 24 concerns raised, 20 addressed.
Background
For the browser target (the default), bun build replaces events and domain with the files in src/node-fallbacks.
Node puts util.inspect(value) in the message. The polyfill has no inspect.
Considered Unhandled error. for every value (131 B less): a string error then shows only in context.
Downsides
A minified bundle with events grows by 238 B (6,995 to 7,233 B, gzip +122 B). With domain, by 516 B.
A listener now gets undefined or null where it got an Error. A catch gets an Error where it got the raw value, also around d.run(). An object (a DOM Event) has no text in the message.
Inside d.run(), d.bind() and d.intercept(), the domain's own "error" listener now gets the ERR_UNHANDLED_ERROR wrapper. Node, bun 1.4.4 and main hand it the raw value.
Notes
Origin.#48481 lists this defect under "Not covered". Its comparison with Node met it in random call sequences. There is no user report and no issue. The case for the change is parity with Node, with Bun's runtime module, and with the polyfill up to bun v1.2.13.
Regression. Up to bun v1.2.13 the polyfill was the text of npm events. It passed the arguments through, and it put a value that is not an Error in the context of an Error. #19783 replaced that text in v1.2.14. #16009 made this change in the runtime in two modules, events.ts and domain.ts. This PR carries both to the polyfills.
Script. Node 26.3.0, bun, and a bundle from this PR print the first block. A bundle from bun 1.4.3 and from main prints the second.
import{EventEmitter}from"events";constout={};{conste=newEventEmitter();letgot="not called";e.on("error",(...args)=>{got=args.length===0 ? "no argument" : args.map(a=>(ainstanceofError ? "Error("+a.message+")" : String(a))).join(",");});e.emit("error");out["emit('error') with a listener"]=got;}{conste=newEventEmitter();letgot;e.on("error",(...args)=>{got=args.map(a=>String(a));});e.emit("error",undefined,"second");out["emit('error', undefined, 'second') with a listener"]=got;}{conste=newEventEmitter();lett;try{e.emit("error","str");}catch(err){t=[typeoferr,err?.code??null,err?.message??null];}out["emit('error', 'str') with no listener"]=t;}{conste=newEventEmitter();lett;try{e.emit("error");}catch(err){t=[typeoferr,err?.code??null,err?.message??null];}out["emit('error') with no listener"]=t;}for(const[k,v]ofObject.entries(out))console.log(k+": "+JSON.stringify(v));
emit('error') with a listener: "no argument"
emit('error', undefined, 'second') with a listener: ["undefined","second"]
emit('error', 'str') with no listener: ["object","ERR_UNHANDLED_ERROR","Unhandled error. ('str')"]
emit('error') with no listener: ["object","ERR_UNHANDLED_ERROR","Unhandled error. (undefined)"]
emit('error') with a listener: "Error(Unhandled error.)"
emit('error', undefined, 'second') with a listener: ["Error: Unhandled error.","second"]
emit('error', 'str') with no listener: ["string",null,null]
emit('error') with no listener: ["object",null,"Unhandled error."]
The test. One script runs as a browser bundle (the polyfills) and as a bun bundle (the runtime modules). Both must print the same 25 lines. The second run passes without the fix: it is the check that the hand copy and the runtime module stay equal. On bun 1.4.3, 19 of the 25 lines differ in the browser bundle. A third case holds what the polyfill does where Node needs inspect. It runs minified, and 5 of its 6 lines differ on 1.4.3. Node prints the same 25 lines, but for one: it wraps an Error of another realm.
Where the message differs from Node. Of 42 sample values, 24 get Node's text: numbers, booleans, undefined, null, bigints, symbols, and strings that need no escape. The others:
An object or a function: Unhandled error. with the value in context. Node prints util.inspect(value). String(value) and Object.prototype.toString run code of the value (toString, a Symbol.toStringTag getter, a Proxy trap).
A string with ', a backslash, a line break, a control character or a lone surrogate: Node picks another quote or escapes. The polyfill prints the string between '.
A string of more than 10,000 characters: both cut there. Node adds ... N more characters.
-0 prints 0.
String(error) has no [ERR_UNHANDLED_ERROR] after the name.
The inspect of the util polyfill (npm util 0.12.5) does not help. It adds 6.1 KB to a minified bundle (7,233 to 13,343 B). For 9 of 16 sample values it prints a text that Node does not print, for example {} for a bigint, a symbol and a Map.
What counts as an Error.Error.isError?.(er) || er instanceof Error.
Node asks er instanceof Error only. It wraps an Error of another realm (an iframe, a vm context), with the text of that Error in the message. The polyfill cannot print that text, so it throws the Error as it is, as a bundle from bun 1.4.3 and the runtime module do. node:events, node:assert: throw the error itself when it inherits from Error.prototype #45255 (open) makes the runtime module accept both kinds too.
Where Error.isError does not exist, an Error of another realm is in the context of an Unhandled error. (the last line of the third test case).
instanceof runs the getPrototypeOf trap of a Proxy, as in Node. For a Proxy that is its own prototype, instanceof throws a RangeError in V8 and does not return in JavaScriptCore. On main, emit() throws such a value at once.
An object that inherits from Error.prototype and a DOMException are thrown as they are.
The domain polyfill. The polyfill is the package domain-browser. d.add(e) attaches a listener that forwards the value of e.emit("error", value) to the domain.
For the 6 falsy values (none, undefined, null, false, 0, ""), the domain listener gets an ERR_UNHANDLED_ERROR in Node. On main it gets an Error with no code for 3 of 6, by the made-up Error. With the events change alone it gets the raw value for 6 of 6. With the forwarder it gets the ERR_UNHANDLED_ERROR for 6 of 6. These are the seven emits of Node's test-event-emitter-no-error-provided-to-error-event.js: 6 of 7 hold on bun 1.4.3, 7 of 7 with this PR.
Not ported: domainEmitter, domain and domainThrown on the error. e.emit() returns true, where Node returns false, as before.
Intentional exclusion: d.run(), d.bind() and d.intercept() of domain-browser catch what the function throws and call d.emit("error", value). With no "error" listener on the domain, a thrown value that is not an Error now reaches the caller in an ERR_UNHANDLED_ERROR (15 of 15 probes). Node has no try there, and the caller gets the raw value (15 of 15). A bundle from main gives the raw value for 9 of 15. Bun's runtime node:domain gives the ERR_UNHANDLED_ERROR for 15 of 15, as this PR does. To follow Node here, the polyfill must replace domain-browser.
The same three methods, with an "error" listener on the domain, when an emitter with no "error" listener emits inside the function: d.on("error", h); d.run(() => new EventEmitter().emit("error", "str")). In Node an emitter made inside a domain belongs to it, and h gets the emitted value. Here emit() throws, the package catches what was thrown, and h gets that. On main it was the raw value. Now it is the ERR_UNHANDLED_ERROR with the value in context. Of 25 kinds of value, h gets what Node gives it for 16 on main and for 5 with this PR, the same for each of the three methods. The 5 are the Errors. For the 9 falsy values Node gives a bare ERR_UNHANDLED_ERROR, and neither main nor this PR does. A guard in domain.js that hands context to the forwarder gives what Node gives for 75 of 75 of these probes (main: 48 of 75). This PR does not have it.
The stream polyfill uses the same emitter. After stream.emit("error") with no value, the callback of stream.finished() gets undefined, as in Node and in Bun's runtime. On main it gets the made-up Error. A probe of 7 stream lines prints what Node prints. On main, 4 of the 7 differ.
Numbers (main 447ff87 against this PR, bun build --target=browser --minify, gzip -9):
Bundle with events: 6,995 to 7,233 B, gzip 2,359 to 2,481 B. Bundle with stream: 129,216 to 129,456 B. Bundle with domain: 9,227 to 9,743 B (238 B from events, 278 B from domain).
The same events bundle with less message text: 7,102 B (+107 B) with Unhandled error. for every value, 7,161 B (+166 B) with strings named only.
Polyfill text: events.js 11,418 to 11,719 B, domain.js 2,015 to 2,431 B. In the release binary: events.js.zst 2,801 to 2,930 B, domain.js.zst 809 to 907 B.
The two emit() functions have the same text. JavaScriptCore: 112 and 134 bytecode instructions before and after, with the same source hash. V8: 248 and 321 bytes of bytecode before and after.
emitError: 126 to 119 instructions in JavaScriptCore, 343 to 317 bytes of bytecode in V8. unhandledError is 60 instructions and 167 bytes. It runs only when nothing listens for "error".
Error objects made for 1,000 handled emit("error") with no value or null: 1,000 to 0.
domain.create() makes 3 more closures (the forwarder, add, remove). Nothing else is new for each call or for the process.
instructions:u for each call with the JIT off (JavaScriptCore first, then V8, 5 runs each). emit("data", 1): 2,120..2,128 to 2,116..2,123, and 2,011..2,036 to 2,016..2,038. A handled emit("error", err): 3,849..3,859 to 3,744..3,772, and 3,559..3,613 to 3,425..3,448. A handled emit("error"): 6,043..6,079 to 3,632..3,647, and 15,015..15,166 to 3,344..3,423. perf is not installed in the container. The counts come from a perf_event_open wrapper.
The thrown Error has the stack of the emit() call. The raw value had none. Its first frames are unhandledError and emitError.
Code of the value that runs for the message: none in 17 probes (a throwing toString, valueOf, Symbol.toPrimitive, a Symbol.toStringTag getter, a name getter, Proxy traps). The only call is the getPrototypeOf trap from instanceof.
Other checks.
Node's 34 files test-event-emitter-*.js and test-events-*.js, run under node with require("events") mapped to the polyfill text: 15 pass before and after. test-event-emitter-errors.js now passes its first assertion (a string). The second and third pin the inspect text of an object.
process uses the native emitter. process.emit("error", "x") with no listener returns false and reports "x" as an uncaught exception. Node throws an ERR_UNHANDLED_ERROR.
import { errorMonitor } from "node:events" fails the build, because the polyfill has no such named export. The test writes EventEmitter.errorMonitor.
The head of events.js says that the file should be generated from events.ts. That is a decision for a maintainer.
Declined from the self-review.
Leave the domain forwarder out, because no caller of d.add() was found in a browser bundle. This PR changes what that forwarder hands on, so Node's own test would get worse (6 of 7 to 3 of 7).
Ship Unhandled error. for every value until a maintainer asks for more (raised twice). The PR keeps the text for primitives. The numbers for each level are above, so a maintainer can cut it.
…yfill and throw ERR_UNHANDLED_ERROR
The events polyfill wrote a made-up Error into the arguments before it
looked for listeners. "error" and errorMonitor listeners got a value the
caller never passed. With no "error" listener it threw the first argument
as it was, whatever its type. The polyfill up to bun v1.2.13 did neither.
emitError now has the shape of the one in src/js/node/events.ts. Listeners
get the arguments unchanged. With no "error" listener it throws an Error as
it is. It throws each other value inside an Error with the code
ERR_UNHANDLED_ERROR and the value in context. The message names a
primitive. An object has no text in the message, because the polyfill has
no util.inspect and does not run code of the value.
The domain polyfill forwards the "error" value of an added emitter to the
domain. Node replaces a falsy value there with an ERR_UNHANDLED_ERROR. The
made-up Error hid that for undefined and null, so the forwarder behind
add() and remove() now makes that Error.
Status: the fix is in this PR (#48591). It waits for review.
How it was reproduced. The script in the Notes of the description, built with bun build --target=browser, on bun 1.4.3 and on main:
emit("error") gives an "error" listener a made-up Error("Unhandled error.").
emit("error", "str") with no listener throws the string itself.
node 26.3.0 and bun without a bundle give the listener no argument, and they throw an Error with the code ERR_UNHANDLED_ERROR.
Test.USE_SYSTEM_BUN=1 bun test test/bundler/bundler_browser.test.ts -t NodeEventsEmitError fails 2 of the 3 new cases on bun 1.4.3. bun bd test test/bundler/bundler_browser.test.ts passes on this branch (26 pass, 0 fail).
CI. In build 140182, 184 jobs ran and all 184 passed. The build shows a failure because 4 macOS x64 test jobs expired before an agent took them. They are in the queue again. Four test files failed once and passed on the retry, and this PR touches none of them: test/aot/code-the-compiler-never-saw.test.ts, test/cli/hot/hot.test.ts, test/js/node/test/parallel/test-watch-mode-kill-signal-default.mjs, test/js/bun/websocket/websocket-server.test.ts.
The events fallback now handles unhandled error values and the domain fallback forwards emitter errors. Browser and Bun bundler tests cover these behaviors and additional error values.
Changes
Unhandled error handling
Layer / File(s)
Summary
Error emission and domain forwarding src/node-fallbacks/events.js, src/node-fallbacks/domain.js
emitError invokes monitors and listeners when present. Without error listeners, it throws the result of unhandledError, which preserves native errors and wraps other values. Created domains gain add and remove methods for error forwarding.
Browser and Bun bundler coverage test/bundler/bundler_browser.test.ts
Shared tests cover error listeners, monitors, unhandled errors, once, rejection capture, cross-realm errors, stream completion, and domain behavior. Minified browser tests cover additional value types, long strings, and conversion hooks.
Possibly related PRs
oven-sh/bun#45255: Preserves error values that Error.isError rejects but that inherit from Error.prototype, which is related to this PR’s error identity handling.
Suggested reviewers: alii
Merge Risk: Low · up to 9eccd
The browser events and domain fallbacks now match Bun's runtime for common error-emission cases. Two small gaps remain: forwarded domain errors lack the domain metadata, and a hostile Proxy error can throw its own trap error instead of ERR_UNHANDLED_ERROR. Both are narrow edge cases that can be fixed before or shortly after merge.
Pre-merge checks: 4
Check name
Status
Explanation
Title check
The title clearly describes the main change: preserving emit("error") arguments and throwing ERR_UNHANDLED_ERROR in the events and domain polyfills. It is specific and concise enough for project histo…
Linked Issues check
Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check
Check skipped because no linked issues were found for this pull request.
Description check
The description clearly explains what the PR changes in the browser events and domain polyfills, the motivation, behavior, known limitations, and bundle-size impact. It also documents verification…
Full details: Title check
Explanation
The title clearly describes the main change: preserving emit("error") arguments and throwing ERR_UNHANDLED_ERROR in the events and domain polyfills. It is specific and concise enough for project history.
Full details: Description check
Explanation
The description clearly explains what the PR changes in the browser events and domain polyfills, the motivation, behavior, known limitations, and bundle-size impact. It also documents verification through bundler tests, Node event tests, runtime comparisons, and performance checks. Although it does not use the template headings verbatim, it provides the required information in a complete and relevant structure.
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Actionable comments posted: 2
Fix comments: Fix CodeRabbit comments on this PR
Prompt to fix all issues
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Inline comments:
Review comments at @src/node-fallbacks/domain.js:
- Line 13: Update the error-forwarding path before d.emit so both incoming Error
objects and Errors created for falsy values receive domainEmitter, domain, and
domainThrown metadata, matching the established behavior in
src/js/node/domain.ts; then preserve the existing emission flow.
Review comments at @src/node-fallbacks/events.js:
- Line 425: Update the error check in unhandledError so a throwing instanceof
check does not replace the original value: catch failures from er instanceof
Error and continue to create the ERR_UNHANDLED_ERROR wrapper with the original
er and context intact.
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src/node-fallbacks/domain.js
src/node-fallbacks/events.js
test/bundler/bundler_browser.test.ts
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Problem
emit("error")gives"error"anderrorMonitorlisteners a made-upError("Unhandled error."). With no listener,emit("error", "str")throws the string itself.emitError(src/node-fallbacks/events.js:52) runsargs[0] ??= new Error("Unhandled error.")before it looks for listeners, then throwsargs[0].Fix
emitErrorfollows the one insrc/js/node/events.ts(node: fix all of test-event-emitter #16009): listeners get the arguments unchanged."error"listener it throws an Error as it is. Each other value goes in thecontextof anErrorwithcodeERR_UNHANDLED_ERROR. The message names a primitive:Unhandled error. ('str').domainpolyfill replaces a falsy"error"value of an added emitter with that error, as Node does.test/bundler/bundler_browser.test.ts(3 new cases, 2 fail on bun 1.4.3). Self-reviewed: 24 concerns raised, 20 addressed.Background
bun buildreplaceseventsanddomainwith the files insrc/node-fallbacks.util.inspect(value)in the message. The polyfill has noinspect.Unhandled error.for every value (131 B less): a string error then shows only incontext.Downsides
eventsgrows by 238 B (6,995 to 7,233 B, gzip +122 B). Withdomain, by 516 B.undefinedornullwhere it got anError. Acatchgets anErrorwhere it got the raw value, also aroundd.run(). An object (a DOMEvent) has no text in the message.d.run(),d.bind()andd.intercept(), the domain's own"error"listener now gets theERR_UNHANDLED_ERRORwrapper. Node, bun 1.4.4 and main hand it the raw value.Notes
Origin. #48481 lists this defect under "Not covered". Its comparison with Node met it in random call sequences. There is no user report and no issue. The case for the change is parity with Node, with Bun's runtime module, and with the polyfill up to bun v1.2.13.
Regression. Up to bun v1.2.13 the polyfill was the text of npm
events. It passed the arguments through, and it put a value that is not an Error in thecontextof anError. #19783 replaced that text in v1.2.14. #16009 made this change in the runtime in two modules,events.tsanddomain.ts. This PR carries both to the polyfills.Script. Node 26.3.0,
bun, and a bundle from this PR print the first block. A bundle from bun 1.4.3 and from main prints the second.The test. One script runs as a browser bundle (the polyfills) and as a bun bundle (the runtime modules). Both must print the same 25 lines. The second run passes without the fix: it is the check that the hand copy and the runtime module stay equal. On bun 1.4.3, 19 of the 25 lines differ in the browser bundle. A third case holds what the polyfill does where Node needs
inspect. It runs minified, and 5 of its 6 lines differ on 1.4.3. Node prints the same 25 lines, but for one: it wraps an Error of another realm.Where the message differs from Node. Of 42 sample values, 24 get Node's text: numbers, booleans,
undefined,null, bigints, symbols, and strings that need no escape. The others:Unhandled error.with the value incontext. Node printsutil.inspect(value).String(value)andObject.prototype.toStringrun code of the value (toString, aSymbol.toStringTaggetter, a Proxy trap).', a backslash, a line break, a control character or a lone surrogate: Node picks another quote or escapes. The polyfill prints the string between'.... N more characters.-0prints0.String(error)has no[ERR_UNHANDLED_ERROR]after the name.The
inspectof theutilpolyfill (npmutil0.12.5) does not help. It adds 6.1 KB to a minified bundle (7,233 to 13,343 B). For 9 of 16 sample values it prints a text that Node does not print, for example{}for a bigint, a symbol and aMap.What counts as an Error.
Error.isError?.(er) || er instanceof Error.er instanceof Erroronly. It wraps an Error of another realm (an iframe, avmcontext), with the text of that Error in the message. The polyfill cannot print that text, so it throws the Error as it is, as a bundle from bun 1.4.3 and the runtime module do. node:events, node:assert: throw the error itself when it inherits from Error.prototype #45255 (open) makes the runtime module accept both kinds too.Error.isErrordoes not exist, an Error of another realm is in thecontextof anUnhandled error.(the last line of the third test case).instanceofruns thegetPrototypeOftrap of a Proxy, as in Node. For a Proxy that is its own prototype,instanceofthrows aRangeErrorin V8 and does not return in JavaScriptCore. On main,emit()throws such a value at once.Error.prototypeand aDOMExceptionare thrown as they are.The domain polyfill. The polyfill is the package
domain-browser.d.add(e)attaches a listener that forwards the value ofe.emit("error", value)to the domain.undefined,null,false,0,""), the domain listener gets anERR_UNHANDLED_ERRORin Node. On main it gets anErrorwith nocodefor 3 of 6, by the made-up Error. With the events change alone it gets the raw value for 6 of 6. With the forwarder it gets theERR_UNHANDLED_ERRORfor 6 of 6. These are the seven emits of Node'stest-event-emitter-no-error-provided-to-error-event.js: 6 of 7 hold on bun 1.4.3, 7 of 7 with this PR.domainEmitter,domainanddomainThrownon the error.e.emit()returnstrue, where Node returnsfalse, as before.d.run(),d.bind()andd.intercept()ofdomain-browsercatch what the function throws and calld.emit("error", value). With no"error"listener on the domain, a thrown value that is not an Error now reaches the caller in anERR_UNHANDLED_ERROR(15 of 15 probes). Node has notrythere, and the caller gets the raw value (15 of 15). A bundle from main gives the raw value for 9 of 15. Bun's runtimenode:domaingives theERR_UNHANDLED_ERRORfor 15 of 15, as this PR does. To follow Node here, the polyfill must replacedomain-browser."error"listener on the domain, when an emitter with no"error"listener emits inside the function:d.on("error", h); d.run(() => new EventEmitter().emit("error", "str")). In Node an emitter made inside a domain belongs to it, andhgets the emitted value. Hereemit()throws, the package catches what was thrown, andhgets that. On main it was the raw value. Now it is theERR_UNHANDLED_ERRORwith the value incontext. Of 25 kinds of value,hgets what Node gives it for 16 on main and for 5 with this PR, the same for each of the three methods. The 5 are the Errors. For the 9 falsy values Node gives a bareERR_UNHANDLED_ERROR, and neither main nor this PR does. A guard indomain.jsthat handscontextto the forwarder gives what Node gives for 75 of 75 of these probes (main: 48 of 75). This PR does not have it.domain.jschanges the two factory properties of the package object and keeps its first and last line. node-fallbacks: bind free process and Buffer in the browser polyfills, fix util, process and timers, make require() of assert and events callable #41533 addsexport default domainafter the last line. The two merge in both orders, and the default export has the forwarder.The stream polyfill uses the same emitter. After
stream.emit("error")with no value, the callback ofstream.finished()getsundefined, as in Node and in Bun's runtime. On main it gets the made-up Error. A probe of 7 stream lines prints what Node prints. On main, 4 of the 7 differ.Numbers (main 447ff87 against this PR,
bun build --target=browser --minify,gzip -9):events: 6,995 to 7,233 B, gzip 2,359 to 2,481 B. Bundle withstream: 129,216 to 129,456 B. Bundle withdomain: 9,227 to 9,743 B (238 B fromevents, 278 B fromdomain).eventsbundle with less message text: 7,102 B (+107 B) withUnhandled error.for every value, 7,161 B (+166 B) with strings named only.events.js11,418 to 11,719 B,domain.js2,015 to 2,431 B. In the release binary:events.js.zst2,801 to 2,930 B,domain.js.zst809 to 907 B.emit()functions have the same text. JavaScriptCore: 112 and 134 bytecode instructions before and after, with the same source hash. V8: 248 and 321 bytes of bytecode before and after.emitError: 126 to 119 instructions in JavaScriptCore, 343 to 317 bytes of bytecode in V8.unhandledErroris 60 instructions and 167 bytes. It runs only when nothing listens for"error".Errorobjects made for 1,000 handledemit("error")with no value ornull: 1,000 to 0.domain.create()makes 3 more closures (the forwarder,add,remove). Nothing else is new for each call or for the process.instructions:ufor each call with the JIT off (JavaScriptCore first, then V8, 5 runs each).emit("data", 1): 2,120..2,128 to 2,116..2,123, and 2,011..2,036 to 2,016..2,038. A handledemit("error", err): 3,849..3,859 to 3,744..3,772, and 3,559..3,613 to 3,425..3,448. A handledemit("error"): 6,043..6,079 to 3,632..3,647, and 15,015..15,166 to 3,344..3,423.perfis not installed in the container. The counts come from aperf_event_openwrapper.Errorhas the stack of theemit()call. The raw value had none. Its first frames areunhandledErrorandemitError.toString,valueOf,Symbol.toPrimitive, aSymbol.toStringTaggetter, a name getter, Proxy traps). The only call is thegetPrototypeOftrap frominstanceof.Other checks.
test-event-emitter-*.jsandtest-events-*.js, run under node withrequire("events")mapped to the polyfill text: 15 pass before and after.test-event-emitter-errors.jsnow passes its first assertion (a string). The second and third pin theinspecttext of an object.events.js(node-fallbacks: emit "removeListener" from removeListener() in the events polyfill #48481, Capture rejections from any thenable in the browser node:events polyfill #33369, node:events: one emit() for emitters that capture rejections #47381, node-fallbacks: bind free process and Buffer in the browser polyfills, fix util, process and timers, make require() of assert and events callable #41533, node:events: give the listener of an aborted AbortSignal a trusted abort event, and let dispose() cancel the call #47252, node: $toClass installs the prototype of built-in constructors; EventEmitter reads it with $getPrototypeOf #46197, process: keep the listener limit in_maxListenersand followevents.defaultMaxListeners#41599, bundler: return themodule.exportsexport from require() of an ES module #42092), 0 of 1 fordomain.js(node-fallbacks: bind free process and Buffer in the browser polyfills, fix util, process and timers, make require() of assert and events callable #41533), 0 of 9 for the test file. With node-fallbacks: emit "removeListener" from removeListener() in the events polyfill #48481 and with node-fallbacks: bind free process and Buffer in the browser polyfills, fix util, process and timers, make require() of assert and events callable #41533 merged in, the events cases of both sides pass. This PR and node-fallbacks: emit "removeListener" from removeListener() in the events polyfill #48481 do not depend on each other. The one that lands second has a new baseline for its byte numbers.Not covered.
processuses the native emitter.process.emit("error", "x")with no listener returnsfalseand reports"x"as an uncaught exception. Node throws anERR_UNHANDLED_ERROR.import { errorMonitor } from "node:events"fails the build, because the polyfill has no such named export. The test writesEventEmitter.errorMonitor.events.jssays that the file should be generated fromevents.ts. That is a decision for a maintainer.Declined from the self-review.
domainforwarder out, because no caller ofd.add()was found in a browser bundle. This PR changes what that forwarder hands on, so Node's own test would get worse (6 of 7 to 3 of 7).Unhandled error.for every value until a maintainer asks for more (raised twice). The PR keeps the text for primitives. The numbers for each level are above, so a maintainer can cut it.ERR_INVALID_ARG_TYPE. That helper belongs to node-fallbacks: emit "removeListener" from removeListener() in the events polyfill #48481, and the two PRs merge in either order.