Function are subprograms which are used to compute a value or perform a task.
Type of Function
– Library or Built-in functions Ex: – valueOf( ) , write( ), alert( ) etc
– User-defined functions
- Function name only starts with a letter, an underscore ( _ ).
- Function name cannot start with a number.
- Do not use reserved keywords. e.g. else, if etc.
How Function Call Works
The code inside a function isn‟t executed until that function is called.