react-to-print is incompatible with SystemJS (and ES modules)

[joeldenning]

react-to-print assumes that the React object has Object.prototype as its prototype, since it calls React.hasOwnProperty() and the hasOwnProperty function only exists on the Object.prototype.

https://github.com/gregnb/react-to-print/blob/dab3e2224b526f57130615fb977c42359ff10317/src/index.tsx#L4-L5

However, this assumption is not true of ES modules, nor of SystemJS modules. The ES module spec says that ES modules must have a prototype of null, which means that they do not have the hasOwnProperty function available on them. This issue has been discussed and fixed in a variety of places, including the following links:

• ns prototype is null, but that breaks some things systemjs/systemjs#2147 (comment)
• Upgrading rollup to fix bug with React external. Resolves systemjs/systemjs#2147 TanStack/table#2021
• Upgrading babel and rollup to latest mosch/react-avatar-editor#339
• getInteropBlock() to work with null prototype objects rollup/rollup#3420

I help maintain SystemJS, and a user reported this error originally with us (see https://single-spa.slack.com/archives/C8R6U7MT7/p1602879935124300).

The following code sandbox shows how the react-to-print library dies if provided a React object without Object.prototype as the prototype: https://codesandbox.io/s/blissful-flower-wy5k7?file=/index.html

The fix in this case is to call Object.prototype.hasOwnProperty.call(React, 'useContext'). I'll submit a PR with that fix.

[MatthewHerbst]

Learn something new every day! Published as v2.10.3, thank you 🎉