Breaking change in buffer between 4.7.3 and 4.7.4

Please provide the following when reporting an issue:

• GeoJSON data: https://gist.github.com/garthk/888c7a0b8a464ec02a3bd1c4d08f8882
• Snippet of source code: https://github.com/garthk/turf-buffer-change

There was a breaking change to @turf/buffer in a patch release:

Major version X (X.y.z | X > 0) MUST be incremented if any backwards incompatible changes are introduced to the public API.

The schema is the same, but I strongly disagree with the proposition that a result change this big is backwards compatible.

[cHewN]

We’ve also come across this problem and have implemented the PostGIS solution @jgwconsulting has posted before. We would prefer using Turf.js though 😃

I don’t see a clear example in any of the open issues, so I’ve created a CodeSandbox that displays the problem clearly: https://codesandbox.io/s/multiple-buffers-in-react-leaflet-qc722

You can use the measure tool in the top right corner to see that PostGIS buffer is 100m, where Turf.js is ~89m.

EDIT: I forgot to mention, this is also on the v4.7.3 branch of Turf.js. My best guess is the issue described at the start is for buffers based on a Point, not a Polygon.

@rowanwins the above sandbox also shows another bug when using turf with a FeatureCollection with multiple Features > Polygons. Turf will add a buffer to each Feature, instead of one buffer for the entire Collection. A workaround could be to merge all the Polygons before using turf to find a buffer but maybe this should be an option in the future? Would you like for me to move/add this to a separate issue?

[rowanwins]

Hi @jgwconsulting

Unfortunately there won’t be anything ready in the next fortnight. I’m waiting on a final upstream change to another module that we’ll be using for unions/difference/clipping before I push another release of the alpha. In the meantime I’m working on a standalone buffer module over here which I hope to eventually incorporate here in Turf.