Can't understand my mistake


#1

Here the error message:

Make sure you have defined all the variables!

Heres my code:

var main = function() {
$('.dropdown-toggle').click(function() {
$('.dropdown-menu').toggle();
});

$('.arrow-next').click(function() {
var currentSlide = $('.active-slide');

currentSlide.fadeOut(600).removeClass('active-slide');
nextSlide.fadeIn(600).addClass('.active-slide');
});
};
$(document).ready(main)


#2

1

should be extended with

nextSlide = currentSlide.next;

2

The addClass(), removeClass() and toggleClass()
require the class-name as argument
like

nextSlide.fadeIn(600).addClass('active-slide');

= = = = = = = = = = = = = = = = = = = = = = = =

++ addClass removeClass ++

Every HTML-Element has so called attributes.
One of the possible attributes, is the class-attribute.

If you write the HTML-document, you add the class-attribute
within the Element-Tag by using the syntax
class-keyword = then a string
containing the class-name
OR mutliple class-names which are =separated=from=eachother= by a space

Thus with

 <div class="myClass1 myClass2 myClass3" ></div>

you now have a DIV-Element carrying 3 classes myClass1, myClass2 and myClass3

As part of its CSS-category-of-Methods jQuery gives you the ability
to manipulate this class-attribute
by providing the addClass()-, removeClass()-, toggleClass()-Methods.
You will have to provide the Method at least 1 argument
which is the string VALUE of the class-name.
Thus you have to change
**$('.article').removeClass('.current')
$(this).addClass('.current')**
into
**$('.article').removeClass('current')
$(this).addClass('current')**

The confusion when to use a pre-pending dot or NOT...
In the Cascading Style Sheet syntax,
you have to prepend-a-dot to the classname
so the CSS will interpret it as a class-attribute
So in the file style.css you will find an object
identified by .current,
In this .current object
the background property-key is set to a particular VALUE

jQuery uses the same syntax to identify a class-attribute
like in the jQuery-selector
$(".current") by which this HTML-Element and all it's CHILDREN
are selected into a jQuery-object,

This parent-HTML-Element carries the class-attribute with class-name "current"

Reference::

google search
class site:jquery.com
https://api.jquery.com/category/selectors/
http://api.jquery.com/class-selector/
https://api.jquery.com/element-selector/
http://www.w3schools.com/jquery/jquery_ref_selectors.asp
http://www.w3schools.com/jquery/trysel.asp


#3

It seems you haven't defined nextSlide: add a line var nextSlide = currentSlide.next(); below the line var currentSlide...


#4

Thank you for for help