find location in geoJson polygon

Question

Hii I have a geoJSON file of an area

(COLORADA) USA

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -109.0283203125,
              37.020098201368114
            ],
            [
              -102.06298828125,
              37.020098201368114
            ],
            [
              -102.06298828125,
              40.9964840143779
            ],
            [
              -109.0283203125,
              40.9964840143779
            ],
            [
              -109.0283203125,
              37.020098201368114
            ]
          ]
        ]
      }
    }
  ]
}

and a location

-105.8544607,39.1160152

and I have many geoJSON files of different regions so I want to know the location from the received Condinates

My question

How can I validate that a location (-105.8544607,39.1160152) exist in the polygon or not ?

Answer 1

While Colorado is a trivial case (just compare the East/West corners to your points longitude and North/South with the latitude) I assume that you want to be able to handle non-square states too.

I would use the turf.js library, in particular the BooleanContains method:

 var line = turf.lineString([[1, 1], [1, 2], [1, 3], [1, 4]]);
 var point = turf.point([1, 2]);

 turf.booleanContains(line, point);

Or possibly booleanPointInPolygon:

var pt = turf.point([-77, 44]);
var poly = turf.polygon([[
  [-81, 41],
  [-81, 47],
  [-72, 47],
  [-72, 41],
  [-81, 41]
]]);

turf.booleanPointInPolygon(pt, poly);

I can't see much difference but it probably depends on where your data is coming from and if it is a geometry or a feature.