Convert geodetic latitude to geocentric latitude using WGS 84

GeocentriLatitude.js

function GeocentricLatitude(lat)
{
    // Convert geodetic latitude 'lat' to a geocentric latitude 'clat'.
    // Geodetic latitude is the latitude as given by GPS.
    // Geocentric latitude is the angle measured from center of Earth between a point and the equator.
    // https://en.wikipedia.org/wiki/Latitude#Geocentric_latitude
    var e2 = 0.00669437999014;
    var clat = Math.atan((1.0 - e2) * Math.tan(lat));
    return clat;
}