Adding new global functions
Some of the built-in capabilities of jQuery are provided via what we have been calling global functions. As we've seen, these are actually methods of the jQuery object, but practically speaking, they are functions within a jQuery namespace.
A prime example of this technique is the $.ajax() function. Everything that $.ajax() does could be accomplished with a regular global function called ajax(), but this approach would leave us open for function name conflicts. By placing the function within the jQuery namespace, we only have to worry about conflicts with other jQuery methods. This jQuery namespace also signals to those who might use the plugin that the jQuery library is required.
Many of the global functions provided by the core jQuery library are utility methods; that is, they provide shortcuts for tasks that are frequently needed, but not difficult to do by hand. The array-handling functions $.each(), $.map(), and $.grep() are good examples of these. To illustrate...
