Points

var J0000 = 1721424.5; // Julian date of Gregorian epoch: 0000-01-01 || var J1970 = 2440587.5; // Julian date at Unix epoch: 1970-01-01 || var JMJD = 2400000.5; // Epoch of Modified Julian Date system || var J1900 = 2415020.5; // Epoch (day 1) of Excel 1900 date system (PC) || var J1904 = 2416480.5; // Epoch (day 0) of Excel 1904 date system (Mac)