Add support for parentId as empty string ("")

[gmw-web]

Somewhat related to #11 .

We have a project in which id's are represented as string. We run into problems when parentId === "" (the items are ignored/the tree is not building). We can solve the issue by replacing all empty strings by null, but this is a bit cumbersome.

Would it be possible to support empty strings in addition to null, undefined and 0?

We also noticed that there is no output (warnings/errors) in the console when tree building fails. This could help identify problems early on and would be nice to have :)

[philipstanislaus]

@gmw-web makes sense, I have added support for empty string parentIds as root objects in https://github.com/philipstanislaus/performant-array-to-tree/releases/tag/v1.6.0

Could you give me an example how the tree building fails? Thanks!

[gmw-web]

Wow, that's quick. Thanks a lot for the quick fix! :)

I exaggerated a bit because tree building doesn't really fail.. In our case an empty tree was returned because parentId was an empty string. At first glance this looked like the tree build failed.

What I meant with my 'nice to have' remarks was that it would be great to have some warnings in the console for the following:

• input invalid (does not match config)
• no root node detected, thus no tree is returned
• unable to place node X

[philipstanislaus]

@gmw-web understood – that's a good point.

Tracking orphans has a small runtime penalty though – so I added an option that will trigger an error if orphans are found.

Released in version https://github.com/philipstanislaus/performant-array-to-tree/releases/tag/v1.7.0

Hope that this is useful for you!