Working with dates and times in ServiceNow, especially when time zones are involved, can indeed be complex. This is often highlighted when using ServiceNow’s GlideDateTime class in JavaScript, where confusion between GMT/UTC and Eastern Standard Time (EST) can arise. It’s crucial to understand how GlideDateTime handles these time zones to avoid unexpected behavior in your ServiceNow applications.
ServiceNow’s GlideDateTime object stores date and time values in GMT/UTC internally by default, regardless of the system time zone setting. This internal representation is accessed using the getValue() method. Specifically, the getValue() method retrieves the date and time in the format yyyy-MM-dd HH:mm:ss and in the system time zone, which defaults to UTC. This is important to remember because while your ServiceNow instance might be set to EST, GlideDateTime often operates behind the scenes in UTC.
On the other hand, the getDisplayValue() method provides a date and time representation in the current user’s display format and time zone. This means if a user’s profile or the system setting is configured for EST, getDisplayValue() will show the time converted to EST. This is the value users typically see in the ServiceNow interface.
To further understand time zone handling, GlideDateTime offers the getTZOffset() method. This method returns the time zone offset in milliseconds, allowing you to programmatically determine the difference between UTC and the relevant time zone.
For best practices, especially since the Eureka release of ServiceNow, it’s recommended to utilize local time and UTC methods whenever possible within GlideDateTime. Methods that rely on the Java Virtual Machine time zone can lead to inconsistencies and unexpected outcomes. Using the dedicated local time and UTC methods ensures more predictable and reliable date and time manipulations within your ServiceNow scripts.
In conclusion, while GlideDateTime might seem challenging initially, understanding the distinction between how it stores time internally (UTC via getValue()) and how it presents time to users (localized via getDisplayValue()) is key. Leveraging the provided methods and adhering to best practices like using local time and UTC methods will significantly streamline your date and time handling in ServiceNow development.
Reference: GlideDateTime – ServiceNow Wiki
