transdatum.js

navitime.geo.Util.transDatumJtoW = function() {
    return function(a) {
        var b = a.lat / 1E3 * Math.PI / 648E3, c = a.lng / 1E3 * Math.PI / 648E3, d = 6377397.155 / Math.sqrt(1 - 0.006674372174974933 * Math.sin(b) * Math.sin(b));
        a = (d + 0) * Math.cos(b) * Math.cos(c) - 147.54;
        var c = (d + 0) * Math.cos(b) * Math.sin(c) - -507.26, b = (0.9933256278250251 * d + 0) * Math.sin(b) - -680.47, d = Math.sqrt(a * a + c * c), e = Math.atan(6378137 * b / (6356752.31424518 * d)), b = Math.atan2(b + 42841.311513312336 * Math.sin(e) * Math.sin(e) * Math.sin(e), d - 42697.67270717874 * Math.cos(e) * Math.cos(e) * 
        Math.cos(e));
        a = Math.atan2(c, a);
        return new navitime.geo.LatLng(Math.round(1E3 * b * (648E3 / Math.PI)), Math.round(1E3 * a * (648E3 / Math.PI)))
    }
}();