This also raises the issue of why bother using a function if general objects can return a value?
The reason is fairly obvious but deserves some thought.
Functions Versus Objects
You do have a choice of associating a value with an object as in:
You also can define a function that does the same thing:
The difference is that the function has a natural way to accept arguments. For example, you can write:
but without defining it to be a function you can't write:
In other words, objects can simply represent a value or a state. That value or state can be manipulated by the methods that the object provides but it cannot be modified while it is being used in an expression.
A function, on the other hand, represents a relationship between input data and the result.
Notice also that, while a function is an object, not all objects are functions and in this sense a function is a "bigger" object.
When should you consider using a value associated with an object?
Some might reply "never" as it isn't a common pattern and could be confusing.
However, if an object represents data or something with state then it is a good approach.
var d=Date.now(); alert(d);
The toString function returns the number of milliseconds since the date epoch. A Date object is an ideal example of when to use an object as a value.
When you first encounter filters they seem easy enough - just extract the results you want from the results you have. The trouble is that filters are fun and jQuery pushes the idea beyond the obvious. [ ... ]