GeoConverter. Meter, KiloMeter, Radian

GeoConverter.js

(function() {
    var GeoConverter;
    GeoConverter = (function() {
        var EARTH_MILES = 24902,
            EARTH_KM = 40076,
            DEGREE_KM = EARTH_KM / 360,
            DEGREE_MI = EARTH_MILES / 360,
            DEGREE_M = DEGREE_KM * 1000,
            MILE_METER = 1609.34,
            RADIAN_DEGREE = 57.2957795;
            // X_Y = Z means 1 X = Z * Y;


        function GeoConverter(distance, unit) {
            if (!(this instanceof GeoConverter)) {
                return new GeoConverter(distance, unit);
            }
            this.distance = distance;
            this.unit = unit;
        }
        GeoConverter.prototype.convertToDegree = function() {
            if (this.unit === 'm') {
                return this.distance / DEGREE_M;
            } else if(this.unit === 'km') {
                return this.distance / DEGREE_KM;
            } else if(this.unit === 'radians' || this.unit === 'radian') {
                return this.distance * RADIAN_DEGREE;
            }
            return NaN;
        };
        GeoConverter.prototype.convertToRadians = function() {
            if (this.unit === 'degree') {
                return this.distance / RADIAN_DEGREE;
            }
            return NaN;
        };
        GeoConverter.prototype.convertToMeter = function() {
            if (this.unit === 'radians' || this.unit === 'radian') {
                return this.distance * RADIAN_DEGREE * DEGREE_M;
            }
            return NaN;
        };
        return GeoConverter;
    })();

    if(typeof window !== "undefined" && window !== null) {
        window.GeoConverter = GeoConverter;
    } else {
        module.exports = GeoConverter;
    }
}).call(this);