werun-wxapp/utils/compute.js

function computeDistance(lat1, lng1, lat2, lng2) {
    var radLat1 = (lat1 * Math.PI) / 180.0;
    var radLat2 = (lat2 * Math.PI) / 180.0;
    var a = radLat1 - radLat2;
    var b = (lng1 * Math.PI) / 180.0 - (lng2 * Math.PI) / 180.0;
    var s =
        2 *
        Math.asin(
            Math.sqrt(
                Math.pow(Math.sin(a / 2), 2) +
                Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)
            )
        );
    s = s * 6378.137; // EARTH_RADIUS;
    s = Math.round(s * 10000) / 10000;
    return s;
}

module.exports = {
    computeDistance
};