dillten

const fs = require('fs');

fs.readFile("input.geojson", function(err, data) { 
    if (err) throw err; 
    let track = JSON.parse(data); 

    for (let i = 0; i < track.features[0].geometry.coordinates.length; i++) {
        let timestamp = Date.parse(track.features[0].properties.coordTimes[i])
        track.features[0].geometry.coordinates[i][3] = timestamp
    }

dillten

var mo = require('moment');

function getSecondMonday(startDate) {
  var startOfMonth = mo(startDate).utc().startOf('month').startOf('isoweek');
  var studyDate = mo(startDate).utc().startOf('month').startOf('isoweek').add(2, 'w');

  if (studyDate.month() == startOfMonth.month()) {
    studyDate = studyDate.subtract(1, 'w');
  }
  return studyDate;