zoom calculation from lat, long and km scuare

zoomCalc.js

function calcLong(lat, long, distance) {
  var earth = 6378.137,  //radius of the earth in kilometer
  pi = Math.PI,
  cos = Math.cos,
  m = (1 / ((2 * pi / 360) * earth)) / 1000;  //1 meter in degree

  return long + (distance * m) / cos(lat * (pi / 180));
}

function calcLat(lat, long, distance) {
  var earth = 6378.137,  //radius of the earth in kilometer
  pi = Math.PI,
  m = (1 / ((2 * pi / 360) * earth)) / 1000;  //1 meter in degree

  return lat + (distance * m);
}

function calcPoint(lat, long, distance) {
  return [
    calcLat(lat, long, distance),
    calcLong(lat, long, distance),
  ]
}

function calcBounds(lat, long, distance) {
  let newLat = calcLat(lat, long, distance)
  let diffLat = lat - newLat
  let newLong = calcLong(lat, long, distance)
  let diffLong = long - newLong

  let points = [
    [lat + diffLat, long + diffLong],
    [lat - diffLat, long - diffLong],
    [lat + diffLat, long - diffLong],
    [lat - diffLat, long + diffLong],
  ]

  return points
}

lat = 41.01
long = 28.960278
distance = 5343

console.log(calcBounds(lat, long, distance))