get centroid data with turf.js

get-centroid.js

 var turf = require('turf');
 var fs = require('fs');
 var jsonfile = require('jsonfile');

 var seoulBuildings = JSON.parse(fs.readFileSync('./processed-data/buildings2345.geojson'));

 var seoulBuildingsCentroids = [];
 for (var i = 0, len = seoulBuildings.features.length; i < len; i++) {
  var centroid = turf.centroid(seoulBuildings.features[i]);
  if(centroid.geometry.coordinates[0]) {
    centroid.geometry.coordinates[0] = parseFloat(centroid.geometry.coordinates[0].toFixed(5));
    centroid.geometry.coordinates[1] = parseFloat(centroid.geometry.coordinates[1].toFixed(5));
    centroid.properties = {};
    /* We are throwing all other properties away than the date of approval to make the data lighter */
    centroid.properties.year = seoulBuildings.features[i].properties.year;
    seoulBuildingsCentroids.push(centroid);
  }
}
var objectToWrite = {
  "type":"FeatureCollection",
  "features": seoulBuildingsCentroids
}

jsonfile.writeFileSync('./seoulBuildingsCentroids2345.geojson', objectToWrite);
console.log('saved seoulBuildingsCentroids2345.geojson');