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MessageChannel is not defined #2448

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TheJoshuaEvans opened this issue Dec 5, 2018 · 8 comments
Open

MessageChannel is not defined #2448

TheJoshuaEvans opened this issue Dec 5, 2018 · 8 comments
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feature html living standard

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@TheJoshuaEvans
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Basic info:

I am attempting to use Zombie.js (which uses jsdom) to debug Message Channel generation, but it doesn't seem to be defined. According to the MDN docs, the MessageChannel constructor has support going all the way back to IE10, so it seems strange that it's not supported here

  • Node.js version: 10.10.0
  • jsdom version: 13.0.0

Minimal reproduction case

'use strict';

// Let's see if MessageChannel is supported
let html = `
<!DOCTYPE html>
<body>
  <h1 id='title'>
    Does MessageChannel Exist?
  </h1>
  <script>
    var title = document.getElementById('title');
    try {
      window.channel = new MessageChannel();
    } catch(e) {
      console.log('Error caught: ' + e.message)
    }

    if (window.channel) {
    	title.innerHTML = 'MessageChannel Exists!';
    } else {
    	title.innerHTML = 'MessageChannel Does not Exist :(';
    }
  </script>
</body>
</html>
`;

const { JSDOM } = require('jsdom');
const { window } = new JSDOM(html, {runScripts: 'dangerously'});

console.log(window.eval('document.getElementById("title").innerHTML'));
// Expected -> 'MessageChannel Exists!'
// Actual ---> 'MessageChannel Does not Exist :('

Running the above node file should print the string "MessageChannel Exists!" and produce no errors. However, when running using jsdom a "MesssageChannel is not defined" error is thrown, and the console logs "MessageChannel Does not Exist :("

How does similar code behave in browsers?

Example of working code in JSFiddle:
https://jsfiddle.net/hvLpg6tm/5/

The HTML provided is exactly the same
@TheJoshuaEvans TheJoshuaEvans mentioned this issue Dec 5, 2018
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@GeniaT
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GeniaT commented Mar 25, 2019

Same error, MessageChannel is not defined. Context: I use Jest and run a createWriteStream method from "streamsaver". Does a workaround exist maybe? Thanks

@TheJoshuaEvans
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Unfortunately I did not find a workaround in this library :(

That doesn't mean there isn't one, however...

@bbruneau
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@TheJoshuaEvans Did you find one elsewhere?

@TheJoshuaEvans
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Been a while since I touched this. When I was working on this I wound up just switching to puppeteer and eating the performance cost

@brettz9
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brettz9 commented Sep 29, 2019 •
edited
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Looks like one could just do this as of Node 10.5.0:

window.MessageChannel = require('worker_threads').MessageChannel;

Source: https://nodejs.org/api/worker_threads.html#worker_threads_class_messagechannel

However, one needs to pass Node the --experimental-worker flag.

@domenic domenic mentioned this issue Jul 10, 2020
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@SimenB SimenB mentioned this issue Mar 18, 2021
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@gaearon
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gaearon commented Mar 18, 2021

If someone adds this, there is one concern that I think needs to be resolved.

jsdom sandboxes timers. I.e. setTimeout and setInterval don't hold the Node process hostage if you call window.close(). They're automatically cancelled.

I believe that jsdom should do the same for MessageChannel ports, if it were to add window.MessageChannel. Concretely, window.close() should also close all open ports. Otherwise, the Node process won't exit.

@victor-homyakov victor-homyakov mentioned this issue Apr 12, 2023
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@dominikj111
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I just encountered this issue during my testing, but not sure if we need something else than this:

window.MessageChannel = jest.fn().mockImplementation(() => {
	return {
		port1: {
			postMessage: jest.fn(),
		},
		port2: {
			addEventListener: jest.fn(),
			removeEventListener: jest.fn(),
		},
	};
});

As I don't need to test sending messages in my tests, it works for me. Do you really need text messaging?

@tianjunnew
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window.MessageChannel = jest.fn().mockImplementation(() => {
  let onmessage;
  return {
    port1: {
      set onmessage(cb) {
        onmessage = cb;
      },
    },
    port2: {
      postMessage: data => {
        onmessage?.({ data });
      },
    },
  };
});

works for me

@CarlosCortizasCT CarlosCortizasCT mentioned this issue Sep 4, 2023
Merged
@jerelmiller jerelmiller mentioned this issue Dec 13, 2024
Merged
@ashharrison90 ashharrison90 mentioned this issue Jan 10, 2025
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9 participants
@brettz9 @gaearon @Zirro @bbruneau @TheJoshuaEvans @dominikj111 @GeniaT @tianjunnew and others