2016 Update

Task/Haversine-formula/JavaScript/haversine-formula-2.js

@@ -0,0 +1,36 @@
+((x, y) => {
+    'use strict';
+
+    // haversine :: (Num, Num) -> (Num, Num) -> Num
+    let haversine = ([lat1, lon1], [lat2, lon2]) => {
+        // Math lib function names
+        let [pi, asin, sin, cos, sqrt, pow, round] =
+            ['PI', 'asin', 'sin', 'cos', 'sqrt', 'pow', 'round']
+            .map(k => Math[k]),
+
+            // degrees as radians
+            [rlat1, rlat2, rlon1, rlon2] = [lat1, lat2, lon1, lon2]
+            .map(x => x / 180 * pi),
+
+            dLat = rlat2 - rlat1,
+            dLon = rlon2 - rlon1,
+            radius = 6372.8; // km
+
+        // km
+        return round(
+            radius * 2 * asin(
+                sqrt(
+                    pow(sin(dLat / 2), 2) +
+                    pow(sin(dLon / 2), 2) *
+                    cos(rlat1) * cos(rlat2)
+                )
+            ) * 100
+        ) / 100;
+    };
+
+    // TEST
+    return haversine(x, y);
+
+    // --> 2887.26
+
+})([36.12, -86.67], [33.94, -118.40]);