Can this package be used to avoid ReferenceError: ImageData is not defined?

[lindapaiste]

Issue or Feature

I am trying to run Jest tests on a code where the code itself (not the test) uses an if (variable instanceof ImageData) check. I included setupFiles: ["canvas"] in my jest.config.js file. When running tests, I get an error:

ReferenceError: ImageData is not defined

I know that this is because ImageData is a DOM construct and doesn't exist in the Node.js environment.

The canvas package includes its own implementation of ImageData and I'm wondering if that can be used as a polyfill. I don't get errors when using instanceof checks on HTMLCanvasElement and other DOM elements. Is my setup wrong, or is what I'm trying to do just not possible? And if it's not possible, is there a better way to check whether or not a variable is an ImageData object?

Your Environment

• Version of node-canvas (output of npm list canvas or yarn list canvas):

+-- [email protected]
`-- [email protected]
  `-- @jest/[email protected]
    `-- [email protected]
      `-- [email protected]
        `-- [email protected]
          `-- [email protected] deduped

• Environment
  node v16.13.0 on Windows 10

[LinusU]

I would recommend this package:

https://github.com/node-gfx/image-data

My goal is to use this in node-canvas in the future, it has a lot of tests to make sure that it works exactly the same as in the browser.

Something like this should do:

global.ImageData = require('@canvas/image-data')

[atsikov]

Solution from this comment didn't work me as putImageData threw likely because of a mismatching class.
However turned out everything could be fixed simply adding ImageData from canvas package into global scope

const canvas = require('canvas')

global.ImageData = canvas.ImageData