Here's my worker:

const Worker = require('worker_threads');
const worker = new Worker("function hello () { console.log('hello world');}", { eval: true })
worker.hello() // not correct

I would like to call hello()

How do I do this?

Here's my worker:

const Worker = require('worker_threads');
const worker = new Worker("function hello () { console.log('hello world');}", { eval: true })
worker.hello() // not correct

I would like to call hello()

How do I do this?

• javascript
• node.js

Share Improve this question Follow asked Apr 2, 2020 at 18:17 HarryHarry 55.1k7676 gold badges187187 silver badges270270 bronze badges 1

• If you look at the docs, you'll see that's not how they require Worker – blex Commented Apr 2, 2020 at 18:22

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2 Answers 2

Sorted by: Reset to default 5

Threads municate through passing messages back and forth, for instance:

worker.postMessage("say hello");

Your worker would set up a listener for the message event, and receive the message as the value property of that eevnt:

// In the worker
const { isMainThread, parentPort } = require('worker_threads');
if (!isMainThread) {
    parentPort.on("message", e => {
        // Dispatch here. For instance:
        if (e.value === "say hello") {
            hello();
        }
    };
}
function hello() { /*...*/ }

There's a lot more to messaging back and forth, details in the worker documentation.

you can use worker-messenger on npm to write that style:

import { Worker } from 'worker_threads'
import { ParentMessenger } from 'worker-messenger'
const test = async () => {
    const results = await messenger.callWorker('testFunction_2', 'args', timeout)
    console.log({results});
}
test()