gistfile1.txt

var fs = require("fs"),
    csv = require("csv-parser"),
    stringify = require("csv-stringify"),
    proj4 = require("proj4");

var nypdProj = 'PROJCS["NAD_1983_StatePlane_New_York_Long_Island_FIPS_3104_Feet",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",984250.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-74.0],PARAMETER["Standard_Parallel_1",40.66666666666666],PARAMETER["Standard_Parallel_2",41.03333333333333],PARAMETER["Latitude_Of_Origin",40.16666666666666],UNIT["Foot_US",0.3048006096012192]]';

var stateplane = proj4(nypdProj);

fs.createReadStream("2013.csv")
  .pipe(csv())
  .on('data', function(row) {
    var wgs84 = stateplane.inverse([row.xcoord,row.ycoord]);
    row.lng = wgs84[0];
    row.lat = wgs84[1];
    return row;
  })
  .pipe(stringify())
  .pipe(fs.createWriteStream("2013-with-latlng.csv"));