Other objects which you will never need to extend include the Math object which is simply a repository for mathematical constants and functions, and the Boolean object which is basically a true/false flag.
Some built in objects are more obvious candidates to be extended than others. Some of those where obvious extensions exist include Date, String, Array, and Number.
- Add Days to a Date
- Days or Business Days Difference Between Dates
- Age Last Birthday
- week number
- ISO standard week number
- Julian Day
- Month and Day Names
- Day of Year
- Swatch Beats
- Daylight Saving Time Flag
- format (any date/time format you want)
- Extending Built In Objects
- Creating Objects from Existing Objects
- Creating New Objects Without Copying Existing Ones
- Dot Notation and "this"
- Inheritance and "constructor"
- Associative Array Notation
- Create Method if Doesn't Exist
- "self" and Multiple Objects
- Defining Objects with JSON
- Lazy Definition
- Extending Methods
- Copying Objects
- Private Properties and Privileged Methods
- Public Access to Private Methods
- Chaining Methods