Assuming xerotime is required, the following result was found.
How? We're going to filter out the unix seconds from the date provided by Xero then apply a toTime() function to it. v_XeroTime="/Date(1586995200000+0000)/"; v_StartIndex = v_XeroTime.indexOf("(")+1; v_EndIndex = v_XeroTime.indexOf("+", v_StartIndex);...