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instanceof Error check returns unexpected result #3082

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akphi opened this issue Dec 9, 2020 · 4 comments
Closed

instanceof Error check returns unexpected result #3082

akphi opened this issue Dec 9, 2020 · 4 comments

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@akphi
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akphi commented Dec 9, 2020 •
edited

Basic info:

  • Node.js version: 14.13.0
  • Yarn version: 1.22.5
  • jsdom version: 16.4.0
  • jest version: 26.6.3

Minimal reproduction case

I'm using JSDom via Jest, this is my repo repro
https://github.com/akphi/jest-jsdom-test/blob/main/src/basic.test.js for Jest
https://github.com/akphi/jest-jsdom-test/blob/main/index.js for native JSDOM example

try {
  // invalid URL to be thrown
  const url = new URL("something");
} catch (e) {
  console.log(e instanceof Error); // expect `true` but returns `false`
}

How does similar code behave in browsers?

It behaves as expected in the browser: i.e. instanceof Error returns true

Link: https://codesandbox.io/s/xenodochial-gauss-2cqjx?file=/src/App.tsx

Points to consider

The gist of the problem is by providing an invalid base URL, the package whatwg-url used by jsdom throws a TypeError which gets picked up by my test, but fails my instanceof Error check.

I did a little bit of digging, there are many issues raised regarding sandboxing or instanceof check, though I don't understand fully, I see 2 categories:

  1. Misconfigured JSDom, such as in Implement Blob.stream, Blob.text and Blob.arrayBuffer #2555. But as mentioned, I use Jest with default settings so I hope I did not misconfigured anything here
  2. Something related to sandboxing and the fact that jsdom Error is somehow different than the Error in my instanceof check.
@domenic
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domenic commented Dec 9, 2020

Can you provide a reproduction that doesn't use Jest? We cannot help debug Jest usage.

@akphi
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akphi commented Dec 9, 2020

@domenic Sure! I just updated my repo. The code is this

const jsdom = require("jsdom");
const { JSDOM } = jsdom;

const dom = new JSDOM(`<body>
  <script>
    try {
      // invalid URL to be thrown
      const url = new URL("something");
    } catch (e) {
      console.log(e instanceof Error); // expect true
    }
  </script>
</body>`, { runScripts: "dangerously" });

// `node index.js` prints `false`

@domenic
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domenic commented Dec 9, 2020

Thanks. I guess then this is "Errors and other globals from the outer Node.js environment are still used" from #2727, which is pretty hard to fix.

@akphi
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akphi commented Dec 9, 2020

@domenic gotcha, just want to confirm that! Will close this to track #2727
Thanks!

@akphi akphi closed this as completed Dec 9, 2020
@pord911 pord911 mentioned this issue Nov 1, 2023
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@domenic @akphi