Initial commit

library/LibHelper.js

@@ -0,0 +1,97 @@
+class LibHelper {
+
+  static EARTH_RADIUS_M = 6371000;
+  static EARTH_RADIUS_KM = 6371;
+  static EARTH_RADIUS_MILES = 3959; // 3958.756 || 3959 || 3963
+
+  static setErrMsg(msg) {
+    if (process.env.NODE_ENV == 'development') {
+      return msg;
+    }
+    return '';
+  }
+
+  /**
+   * Calculates the great-circle distance between two points, with
+   * the Haversine formula.
+   * @param float latitudeFrom Latitude of start point in [deg decimal]
+   * @param float longitudeFrom Longitude of start point in [deg decimal]
+   * @param float latitudeTo Latitude of target point in [deg decimal]
+   * @param float longitudeTo Longitude of target point in [deg decimal]
+   * @param float earthRadius Mean earth radius in [m]
+   * @return float Distance between points in [m] (same as earthRadius)
+   * reference: https://stackoverflow.com/questions/14750275/haversine-formula-with-php
+   * tolak ukur: tarik garis lurus
+   * more accurate using km/meters than miles i think ~ rafifmulia
+   */
+  static haversineGreatCircleDistance(latFrom, lngFrom, latTo, lngTo, earthRadius = LibHelper.EARTH_RADIUS_M) {
+    // convert from degrees to radians
+    let latFromRads = LibHelper.degsToRads(latFrom);
+    let lngFromRads = LibHelper.degsToRads(lngFrom);
+    let latToRads = LibHelper.degsToRads(latTo);
+    let lngToRads = LibHelper.degsToRads(lngTo);
+
+    let latDelta = latToRads - latFromRads;
+    let lngDelta = lngToRads - lngFromRads;
+
+    let angle = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(latDelta / 2), 2) + Math.cos(latFromRads) * Math.cos(latToRads) * Math.pow(Math.sin(lngDelta / 2), 2)));
+    let distance = angle * earthRadius;
+
+    return distance;
+  }
+
+  // reference: https://www.codegrepper.com/code-examples/javascript/deg2rad+javascript
+  // degrees to radians
+  static degsToRads(deg) {
+    return (deg * Math.PI) / 180.0;
+  }
+  // radians to degrees
+  static radsToDegs(rad) {
+    return rad * 180.0 / Math.PI;
+  }
+
+  // round up with precisions digits => 4 == (10000)
+  // reference: https://stackoverflow.com/questions/11832914/how-to-round-to-at-most-2-decimal-places-if-necessary
+  static milesToKm(miles, precisionDigits = 10000) {
+    return Math.round(((miles * 1.609) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static milesToMeters(miles, precisionDigits = 10000) {
+    return Math.round(((miles * 1609) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static milesToMiles(meters, precisionDigits = 10000) {
+    return Math.round(((meters) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static kmToMiles(km, precisionDigits = 10000) {
+    return Math.round(((km / 1.609) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static kmToMeters(km, precisionDigits = 10000) {
+    return Math.round(((km * 1000) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static kmToKm(meters, precisionDigits = 10000) {
+    return Math.round(((meters) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static metersToKm(meters, precisionDigits = 10000) {
+    return Math.round(((meters / 1000) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static metersToMiles(meters, precisionDigits = 10000) {
+    return Math.round(((meters / 1609) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+  static metersToMeters(meters, precisionDigits = 10000) {
+    return Math.round(((meters) + Number.EPSILON) * precisionDigits) / precisionDigits;
+  }
+
+  static hex2bin(hex) {
+    return ("00000000" + (parseInt(hex, 16)).toString(2)).slice(-8);
+  }
+
+  static splitEvery4Char(str) {
+    if (str) {
+      str = '' + str;
+      let splitEvery4Char = str.match(/.{1,4}/g)
+      return splitEvery4Char.join(' ')
+    }
+    return '';
+  }
+};
+
+module.exports = LibHelper;