jQuery Cookbook - Cdn.oreilly.com - O'Reilly

Discussion
In this example, we have two arrays that contain a list of horse breeds. The arrays are
combined in the order of first + second. So, the final breeds array will look like this:
['Quarter Horse', 'Thoroughbred', 'Arabian', 'Belgian', 'Percheron']
4.6 Filtering Out Duplicate Array Entries with jQuery.unique
Problem
You have two jQuery DOM collections that need to have duplicate elements removed:
(function($) {
$(document).ready(function() {
var animals = $('li.animals').get();
var horses = $('li.horses').get();
$('#animals')
.append( $(animals).clone() )
.append( $(horses).clone() );
});
})(jQuery);
Solution
(function($) {
$(document).ready(function() {
var animals = $('li.animals').get();
var horses = $('li.horses').get();
var tmp = $.merge( animals, horses );
tmp = $.unique( tmp );
$('#animals').append( $(tmp).clone() );
});
})(jQuery);
Discussion
jQuery’s $.unique() function will remove duplicate DOM elements from an array or
collection. In the previous recipe, we combine the animals and horses arrays using
$.merge(). jQuery makes use of $.unique() throughout most of its core and internal
functions such as .find() and .add(). Thus, the most common use case for this method
is when operating on an array of elements not constructed with jQuery.
4.7 Testing Callback Functions with jQuery.isFunction
Problem
You have written a plugin and need to test whether one of the settings is a valid callback
function.
82 | Chapter 4: jQuery Utilities