cleanCoords() omits valid coords.

[erikh2000]

If you agree with me this is a bug, I can add a PR for a test case and maybe a fix.

const coords = {type:'Polygon', coordinates:[[[0,0],[2,2],[3,30],[3,30],[3,30],[4,4],[0,0]]]};
const expected = {type:'Polygon', [[[0,0],[2,2],[3,30],[4,4],[0,0]]]};
expect(cleanCoords(coords)).toEqual(expected); // Fails

The actual returned value is: {type:'Polygon', [[[0,0],[1,10],[2,2],[4,4],[0,0]]]}

In other words, it omits the [3,30] point. The reason it does this is that there is a duplicate coordinate of 3,30. When isPointOnLineSegment() evaluates either of the two cases of 3,30, it correctly returns true. But if I understand the contract of cleanCoords(), it should preserve one of the 3,30 coords.

And I think that would be a useful and expected contract to keep. Because then you can do things like @DenisCarriere 's earlier fix for intersect() which truncated the coord precision and then ran cleanCoords() to yank redundant points.

[rowanwins]

Indeed looks like a bug @erikh2000 - thanks for reporting

[SimonsUnikaNamn]

I am still getting this error, https://jsfiddle.net/eag6dvzk/1/