Distance between two points over a path with turf.js

Question

It's possible to calculate the distance between two points over a line path using turfjs? How?

Answer 1

Slice the line using your two points using turf.lineSlice. This will return a new line which consists of just the sections on the line between your two points. Next you can use turf.lineDistance to calculate the distance of that sliced line.

var line = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "LineString",
        "coordinates": [
          [4.0155029296875, 40.18726672309203 ],
          [4.0814208984375, 40.195659093364654 ],
          [4.15283203125, 40.19146303804063 ],
          [4.185791015625, 40.17887331434696 ],
          [4.2242431640625, 40.15788524950653 ],
          [4.273681640625, 40.111688665595956 ],
          [4.3011474609375, 40.06125658140474 ],
          [4.290161132812499, 40.02340800226773 ],
          [4.3341064453125, 39.97291055131899 ],
          [4.4000244140625, 39.96870074491696 ],
          [4.4659423828125, 39.977120098439634 ],
          [4.531860351562499, 40.002371935876475 ],
          [4.5648193359375, 40.052847601823984 ],
          [4.5648193359375, 40.11588965267845 ]
        ]
      }
    }
  ]
};

var start = {
  "type": "Feature",
  "properties": {},
  "geometry": {
    "type": "Point",
    "coordinates": [4.2400360107421875, 40.143189742924406 ]
  }
};
var stop = {
  "type": "Feature",
  "properties": {},
  "geometry": {
    "type": "Point",
    "coordinates": [4.3059539794921875, 40.00815750046493 ]
  }
};

var sliced = turf.lineSlice(start, stop, line.features[0]);
var length = turf.lineDistance(sliced, 'kilometers');