Insert Date and time with second or millisecond using RESTAPI

Hi All,

I want Insert Date and time with second or millisecond using RESTAPI

Note:-Data Type is Dateandtime

Currently i am getting Minutes only , below is my code:-

var new_tracker = {};
new_tracker.new_CurrentStatus = "date new tracker data ";
new_tracker.new_name = "This tracker was created by the JavaScriptRESTDataOperations sample.";

new_tracker.new_StartTime = new Date();   HERE IS MY VARIABLE TO INSERT for date time

SDK.REST.createRecord(
new_tracker,
"new_tracker",
function (new_tracker) {
retrieveTracker(new_tracker.new_trackerid)
},
errorHandler
);