Add jitter to latitude/longitude

lat_lng_jitter.js

//
// Make a few assumptions and add noise to latitude/longitude position
// Ex, console.log(jitter(-26.4853429150483, -49.072945734375, 5));
//

var rad_Earth  = 6378.16;
var one_degree = (2 * Math.PI * rad_Earth) / 360;
var one_km     = 1 / one_degree;

function randomInRange(from, to, fixed) {
  fixed = fixed || 10;
  return (Math.random() * (to - from) + from).toFixed(fixed) * 1;
}

function jitter(lat, lng, kms, fixed) {
  return {
    lat : randomInRange(
      lat - (kms * one_km),
      lat + (kms * one_km),
      fixed
    ),
    lng : randomInRange(
      lng - (kms * one_km),
      lng + (kms * one_km),
      fixed
    )
  };
}