Run results for: Haversine Distance tests

Test name	Executions per second
✓ Haversine Optimized	134,282,224 Ops/sec
Haversine Mine ASin	132,451,312 Ops/sec
Haversine Classic	131,814,264 Ops/sec
Haversine Mine ATan	127,653,024 Ops/sec
Spherical Law of Cosines	124,143,352 Ops/sec
Equirectangular (a little less accurate)	119,387,032 Ops/sec

Script Preparation code:

var EARTH_RADIUS_M = 6371e3;
var EARTH_DIAMETER_M = EARTH_RADIUS_M * 2;
var DEG_TO_RAD = Math.PI / 180;
var p1 = { lat: 43.63625, lon: -79.40454 };
var p2 = { lat: 43.69851, lon: -79.39699 };

function haversineClassic(lat1, lon1, lat2, lon2) {
  var φ1 = lat1 * DEG_TO_RAD;
  var φ2 = lat2 * DEG_TO_RAD;
  var Δφ = (lat2-lat1) * DEG_TO_RAD;
  var Δλ = (lon2-lon1) * DEG_TO_RAD;

  var a = Math.sin(Δφ/2) * Math.sin(Δφ/2) +
          Math.cos(φ1) * Math.cos(φ2) *
          Math.sin(Δλ/2) * Math.sin(Δλ/2);
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

  var d = EARTH_RADIUS_M * c;
  
  return d;
}

function haversineOptimized(lat1, lon1, lat2, lon2) {
  var p = 0.017453292519943295;    // Math.PI / 180
  var c = Math.cos;
  var a = 0.5 - c((lat2 - lat1) * p)/2 + 
      c(lat1 * p) * c(lat2 * p) * 
      (1 - c((lon2 - lon1) * p))/2;

  return 12742 * Math.asin(Math.sqrt(a)); // 2 * R; R = 6371 km  
}

function haversineMineATan(lat1, lon1, lat2, lon2) {
  var fDP = Math.sin( (lat2 - lat1) * DEG_TO_RAD / 2 );
  var fDL = Math.sin( (lon2 - lon1) * DEG_TO_RAD / 2 );
  var fP1 = Math.cos( lat1 * DEG_TO_RAD );
  var fP2 = Math.cos( lat2 * DEG_TO_RAD );
  var a = fDP * fDP + fP1 * fP2 * fDL * fDL;
  return EARTH_DIAMETER_M * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
}
function haversineMineASin(lat1, lon1, lat2, lon2) {
  var fDP = Math.sin( (lat2 - lat1) * DEG_TO_RAD / 2 );
  var fDL = Math.sin( (lon2 - lon1) * DEG_TO_RAD / 2 );
  var fP1 = Math.cos( lat1 * DEG_TO_RAD );
  var fP2 = Math.cos( lat2 * DEG_TO_RAD );
  var a = fDP * fDP + fP1 * fP2 * fDL * fDL;
  return EARTH_DIAMETER_M * Math.asin(Math.sqrt(a));
}

function spherical(lat1, lon1, lat2, lon2) {
  var φ1 = lat1 * DEG_TO_RAD, φ2 = lat2 * DEG_TO_RAD, Δλ = (lon2-lon1) * DEG_TO_RAD;
  return Math.acos( Math.sin(φ1) * Math.sin(φ2) + Math.cos(φ1) * Math.cos(φ2) * Math.cos(Δλ) ) * EARTH_RADIUS_M;
}

function equirectangular(lat1, lon1, lat2, lon2) {
  var x = (lon2-lon1)*DEG_TO_RAD * Math.cos( (lat1+lat2)*DEG_TO_RAD/2 );
  var y = (lat2-lat1)*DEG_TO_RAD;
  return EARTH_RADIUS_M * Math.sqrt( x*x + y*y )
}

Tests:

Haversine Classic
haversineClassic(p1.lat, p1.lon, p2.lat, p2.lon);
Haversine Optimized
haversineOptimized(p1.lat, p1.lon, p2.lat, p2.lon);
Haversine Mine ATan
haversineMineATan(p1.lat, p1.lon, p2.lat, p2.lon);
Haversine Mine ASin
haversineMineASin(p1.lat, p1.lon, p2.lat, p2.lon);
Spherical Law of Cosines
spherical(p1.lat, p1.lon, p2.lat, p2.lon);
Equirectangular (a little less accurate)
equirectangular(p1.lat, p1.lon, p2.lat, p2.lon);

Run results for: Haversine Distance tests

Haversine Classic

Haversine Optimized

Haversine Mine ATan

Haversine Mine ASin

Spherical Law of Cosines

Equirectangular (a little less accurate)