React: "React.createElement: type is invalid" warning in IE11 when using React.Fragment

[XaveScor]

https://codesandbox.io/embed/j30o67kpxy
React shows warning in console if I use React.Fragment

Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: object.

[gaearon]

Yeah, this is a false positive warning. It only appears if you use a Symbol polyfill.

I think it happens because we validate types here:

https://github.com/facebook/react/blob/8ce53671eddc8e96a51d87c9b1ad8cd0532ff9d5/packages/react/src/ReactElementValidator.js#L273-L277

React.Fragment is a symbol. However, if Symbol is polyfilled, then its typeof won't be 'symbol'—it will be just 'object'. So this condition won't be true.

To get around this, I think we should compare type directly to React.Fragment before concluding it's invalid.

[AyWa]

I would like to work on it, if it is possible :)

[gaearon]

Sure, it's yours.

[gaearon]

@AyWa We didn't get a PR, so the submitter has fixed the issue.

[AyWa]

@gaearon Yeah I saw yesterday that the PR was already made. Sadly I planed to work on it this week.
Anyway I hope I can find a good first issue soon ;)

[dereklieu]

Glad this is fixed. Any way this can make it into a release soon?

[gaearon]

We'll likely cut a release in a week or so.

[gaearon]

In the meantime if this is blocking you, you can yarn build -- dom from master and grab the builds from build/dist.

[XaveScor]

@dereklieu You can use https://www.npmjs.com/package/@xavescor/react package while new version is not released.

[danwad]

@gaearon Any update on when we are expecting this fix to land on npm?

[XaveScor]

@danwad C'mon build own react package until 16.3 release. It's several lines in your webpack config.

[gaearon]

We plan a release within a week or so.