Javascript which converts a Date object into an ISO 8601 formatted string - 'YYYY-MM-DDTHH:mm:ss.sssZ' - with a fallback for when the function 'toISOString' doesn't exist (e.g. IE 8 or less).

Usage:
var now = new Date;
console.log(now.toISOString());

Validates clean in JSLint (Edition 2012-12-31).