child_process.fork a ts file with import statement and args && execArgv !== undefined

index.ts

import { fork } from 'child_process';

const proc = fork('test.ts', [], { execArgv: [] })
proc.on('message', message => console.log(message))

test.ts

import * as test from 'fs';

console.log('File loaded')

Note: You need ts-node, typescript, and @types/node
I was using node version 10.4.1

It will work if you:
Remove test.ts's import statement,
Change either empty array to undefined in index.ts,
Or use vanilla js/compiled typescript

PS C:\Users\ShayB\Desktop> node -r ts-node/register index.ts
C:\Users\ShayB\Desktop\test.ts:1
(function (exports, require, module, __filename, __dirname) { import * as test from 'fs';
                                                                     ^

SyntaxError: Unexpected token *
    at new Script (vm.js:74:7)
    at createScript (vm.js:246:10)
    at Object.runInThisContext (vm.js:298:10)
    at Module._compile (internal/modules/cjs/loader.js:670:28)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:713:10)
    at Module.load (internal/modules/cjs/loader.js:612:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:551:12)
    at Function.Module._load (internal/modules/cjs/loader.js:543:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:744:10)
    at startup (internal/bootstrap/node.js:238:19)
PS C:\Users\ShayB\Desktop> node -r ts-node/register index.ts

Note: the error is not the * it will be at the same spot no matter what you import.

I actually ran into this in a real project too, incredible.

You're overriding execArgv which means this isn't even running through TypeScript.

Please read the documentation for functions you're trying to use: https://nodejs.org/api/child_process.html#child_process_child_process_fork_modulepath_args_options.

execArgv <string[]> List of string arguments passed to the executable. Default: process.execArgv

child_process.fork() will spawn new Node.js instances using the process.execPath of the parent process.

I think the real issue here is child_process.fork() forks a new Node.js instance, but it is unaware of ts-node.

I have the same problem and the title containing things like args and execArgv is really leading in the wrong direction.

I'm also running my code via ts-node. In it I need to create a child proc with fork().

If I run code like child_process.fork('ChildProcess.ts') and ChildProcess.ts contains some typescript only constructs (eg: import {}, export, ...), then the interpreter being node, not ts-node, will fail.

It may be recommended to use something like child_process.exec('node ./node_modules/.bin/ts-node my-typescript-module.ts), but I really want/need the IPC communication channel that gets set up between the parent and child processes when fork() specifically is used.

Any ideas on how to achieve this?

@jrhite

@jrhite This should work:

const childProcess = fork(join(__dirname, 'child-process.ts'), ['-r', 'ts-node/register']);`

This is what worked for me.

fork(
  'child-process.ts'
  , []
  , {
    execArgv: ['-r', 'ts-node/register']
  }
)

@RichAyotte

I know this is old, but hopefully it helps someone.

@RichAyotte's response worked for me. In my case I needed to specify the relative path to the file:
const childProcess = fork("./src/controllers/child-process.ts", [], { execArgv: ["-r", "ts-node/register"] });

Heads up: This should never have been an issue. If you are encountering an issue please let me know by creating a new issue.

I did additional work in January to ensure args from the ts-node executable also forward correctly to children: #760.

Edit: The original issue is still valid though, if you override execArgv it won't be able to use the default behavior of re-using ts-node.

You can also omit the extension, once compiled the resulting JavaScript will be used. Ex.

ParentProcess.ts

  import * as child_process from 'child_process';
  import * as path from 'path';
  
  let ChlidProcessPath = path.resolve(__dirname + "/ChildProcess")
  child_process.fork(ChlidProcessPath, [], { stdio: ['inherit', 'inherit', 'inherit', 'ipc'] });

ChlidProcess.ts

class ChildProcessClass {
    constructor() {
        console.log("forked!"); 
    }
}
new ChildProcessClass();

How can I use ts-node-dev instead of ts-node?

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child_process.fork a ts file with import statement and args && execArgv !== undefined #619

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child_process.fork a ts file with import statement and args && execArgv !== undefined #619

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blakeembrey commented on Jun 29, 2018

jrhite commented on Sep 29, 2018

RobinBuschmann commented on Jan 11, 2019

RichAyotte commented on Jul 15, 2019

Perry5 commented on Sep 15, 2019

blakeembrey commented on Sep 15, 2019

carlosalaniz commented on Jan 6, 2021

Alexzanderk commented on Apr 25, 2021

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