Question

I added the following function so I could iterate backwards over some collections:

jQuery.reverseEach = function (object, callback, args) {
    var reversed = $(object).get().reverse();
    return $(reversed).each(callback, args);
};

Which works great if you call it like this:

$.reverseEach($('#selectedSortItems option:selected'), function() {
    $(this).insertAfter($(this).next());
});

However, I wanted to be all slick and make it chainable because I like my syntactic sugar. I added a reference to the original reverseEach function on jQuery’s prototype:

jQuery.prototype.reverseEach = function(callback, args) {
    return jQuery.reverseEach(this, callback, args);
};

And now I can call it like this:

$('#selectedSortItems option:selected').reverseEach(function () {
    $(this).insertAfter($(this).next());
});

However, I thought that the jQuery.fn.extend function does the same thing in a single step, without the need to reference prototype. I tried to use the jQuery.fn.extend function, like this:

jQuery.fn.extend({
    reverseEach: function(object, callback, args) {
        var reversed = $(object).get().reverse();
        return $(reversed).each(callback, args);
    }
});

But whenver I run the chained method that way, I get the following error:
Unable to get value of the property ‘call’: object is null or undefined.

What am I doing wrong with the jQuery.fn.extend method? Am I taking the complete wrong approach, or am I just missing something simple?

Thanks!

Answer 1

You dont need to access the protype you jsut define on $.fn:

(function($){
  $.fn.reverseEach = function(callback) {
     return $(this.get().reverse()).each(callback);
  };
})(jQuery);