Regex to test whether the decimal fraction seconds is found or not in ISO 8601 datetime string

regex-to-test-decimal-fraction-second-in-iso-8601.js

// the regex is generated using https://txt2re.com
// Time Stamp 1
var re1='((?:2|1)\\d{3}(?:-|\\/)(?:(?:0[1-9])|(?:1[0-2]))(?:-|\\/)(?:(?:0[1-9])|(?:[1-2][0-9])|(?:3[0-1]))(?:T|\\s)(?:(?:[0-1][0-9])|(?:2[0-3])):(?:[0-5][0-9]):(?:[0-5][0-9]))';
// Any Single Character 1
var re2='(\\.)';
// Any Single Digit 1
var re3='(\\d)';
// Any Single Digit 2
var re4='(\\d)';
// Any Single Digit 3
var re5='(\\d)';
// Any Single Word Character (Not Whitespace) 1
var re6='(Z)';

var p = new RegExp(re1 + re2 + re3 + re4 + re5 + re6, ["i"]);

var txt = '2016-11-09T16:00:00Z';
// false
console.log('p.test(txt)', p.test(txt));

txt = '2016-11-09T16:00:00.000Z';

// true
console.log('p.test(txt)', p.test(txt));