「captureRejections」 property not works in ts-node

[Scared-Heart]

Search Terms

I wanna create a eventEmitter with 「captureRejections」
it works in with node.js
but not works with ts-node

Expected Behavior

create a eventEmitter instance with able to capture promise rejections with ts-node

Actual Behavior

「captureRejections」property not work with ts-node
but works with node

Steps to reproduce the problem

create a file testEvent.js

const { EventEmitter } = require('events');
const ee = new EventEmitter({ captureRejections: true });
console.log(ee)

run

ts-node testEvent.js

check console output

EventEmitter {
  _events: [Object: null prototype] {},
  _eventsCount: 0,
  _maxListeners: undefined,
  [Symbol(kCapture)]: false
}

[Symbol(kCapture)]: false means 「captureRejections」property is not setted

however, when i use node

run

node testEvent.js

console output

EventEmitter {
  _events: [Object: null prototype] {},
  _eventsCount: 0,
  _maxListeners: undefined,
  [Symbol(kCapture)]: true
}

[Symbol(kCapture)]: false means 「captureRejections」works

this is so confusing

Minimal reproduction

Specifications

• ts-node version: v10.4.0

• node version: v14.15.0

• TypeScript version: 4.4.4

• tsconfig.json, if you're using one: not use

• Operating system and version: macos 10.15.5 (19F101)

[Scared-Heart]

captureRejections doc
https://nodejs.org/docs/latest-v14.x/api/events.html#events_events_capturerejections

[cspotcode]

I'm unable to reproduce this. Usually when that happens, it means the reporter was making an honest mistake.

I've labelled this issue "needs more information" and I'll close in a few days if I don't hear back.

[Scared-Heart]

I'm unable to reproduce this. Usually when that happens, it means the reporter was making an honest mistake.

I've labelled this issue "needs more information" and I'll close in a few days if I don't hear back.

const emitter = require('events')
const em1 = new emitter({ captureRejections: true })
console.log(em1)

I tried the code above on online runtime node.js again and it reproduced(node -v 14.x), 「captureRejections」property is setted with value true, the same result with my local test.
however, then i use local node.js REPL, it's different, 「captureRejections」property is false.
run with ts-node, 「captureRejections」is always setted with false.

So, first question is should ts-node works the same with node in 「experimental features」?
if that's true, i guess this is a problem need 2 be fixed cause it's a trap for dev.
second question is why node REPL works different with node $fileName.js ?
maybe i should create a issue for node?

[cspotcode]

Sounds like you've narrowed this down to a bug in the behavior of whatever version of node you have installed locally, is that right?

[Scared-Heart]

Sounds like you've narrowed this down to a bug in the behavior of whatever version of node you have installed locally, is that right?

emm, it's just a clue when i saw your reply and tried again. Cause i guess, if you reproduced this code with node REPL then it's not right.

I tried with node version 12-17, it works fine with captureRejections property, but node REPL is wrong.

what i expected is that then i run this code with ts-node, it works the same as node, captureRejections can be applied to eventEmitter.

[cspotcode]

I see, you are saying that the node REPL exhibits this bug? Then it is a node bug?

I modified your testEvent.js

// For some reason, the following import triggers this bug.
// If this import is removed, the bug goes away.
require('repl');

const { EventEmitter } = require('events');
const ee = new EventEmitter({ captureRejections: true });
console.log('Event emitter created with captureRejections: true, so `Symbol(kCapture) should be true');
console.log(ee);

And the bug reproduces on the latest node v17.3.0:

❯ node -v
v17.3.0

❯ node ./testEvent.js
Event emitter created with captureRejections: true, so `Symbol(kCapture) should be true
EventEmitter {
  _events: [Object: null prototype] {},
  _eventsCount: 0,
  _maxListeners: undefined,
  [Symbol(kCapture)]: false
}

[Scared-Heart]

exactly! I agree that it's a node bug. And i don't know how ts-node works different too, maybe caused by node.js 'repl' module.

[cspotcode]

When ts-node is loaded, it requires node's built-in 'repl' module. Importantly, this does not necessarily mean it creates a REPL.

ts-node/src/index.ts

Lines 29 to 34 in aff9bb9

	export {
	createRepl,
	CreateReplOptions,
	ReplService,
	EvalAwarePartialHost,
	} from './repl';

ts-node/src/repl.ts

Lines 4 to 9 in aff9bb9

	import {
	Recoverable,
	ReplOptions,
	REPLServer,
	start as nodeReplStart,
	} from 'repl';

This bug is triggered merely by require('repl'), which is why the bug occurs even when we are not using the REPL at all.

Because this is a node bug, I'm going to close this issue. Good luck!

[CMCDragonkai]

I can confirm this is a node bug as well. Has anybody created an issue upstream?

[CMCDragonkai]

Oh I found it nodejs/node#41391