Custom Date and Time formatting in JavaScript like in .NET C# or VB.NET Introduction A date and time format string defines the text representation of a Date() object, that results in a custom format string . Any string that is not a standard date and time format string is interpreted as a custom date and time format string . You can download the format.date JavaScript Utility, an application that enables you to apply format string s to date and time values and displays the result in string format. Background In formatting operations, custom date and time format string s can be used with the format method of a Date() instance . The format method requires that an input string conforms exactly to a particular pattern for the parse operation to succeed, otherwise it will give you an error ( e.g. ERROR: Not supported method [method name] ). The following table describes the custom date and time format and displays a result string produced by each forma