Safari support <=13 is completely broken.

[l-you]

We use react-intersection-observer in our NextJS app.
Recently, we discovered that our website is broken in all Safari browsers prior to iOS 13.4.

The root of the problem is that ES2020 features (such a constructor and ()=>{} syntax) are omitted in the production code.
Browser: IOS Safari 13.4
Device: All IPhones
Testing source: Browserstack

Question is:
Is it expected behaviour to omit the latest ESM features in the react-intersection-observer?
If so, why is it not specified in the documentation?

For those who are looking for solution.
You can work around it by using the transpilePackages field in next.config.js.

Screenshot below shows code included in our NextJS bundle.

Screenshot of browser console.

[thebuilder]

Could you try the latest release? It downgrades the bundle output to ES2018, which should also fix this.
#635

[thebuilder]

Is it expected behaviour to omit the latest ESM features in the react-intersection-observer?

The question is what baseline target should be supported in packages. There's no definite answer to this.

[thebuilder]

Fixed by #636