Class: "Description" versus "description row" 4/10


#1

The hint tells us to select "description" for $(".description").hide(), but the actual name of the class in html is "description row".

Can anyone explain to me why this works?

Thanks so much!


#2

If you find a HTML-Element having the class-attribute set like

<div class="description row">

it means that for this HTML-Element you have 2 class-name's =description= and =row=
( the used =separator= is a < space> character )

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

If you use $( )
you are using the so called jQuery selector

The selector will select ALL the HTML-Elements of the active HTML-page,
which have attribute you use as an argument.

Thus if you use
$(".article") you are selecting all the HTML-Element's
which have the class="article" set
( you will find 7 Article's)

The jQuery Selector will create an object
which will contain all those selected Elements. AND its children..

Talking in terms of DOM (=Document Object Model )
you select a parent and all its children which are in its tree

Here is the how the Document Object Model view looks like for
this HTML-page..

                   html
                    |
      + - - - - - - + - - - - - -+
      |                          |
      3                          7
     head                       body
      |                          |
  + - + - +          + - - - - - + - - - - - - +
  |       |          |           |             |
  4       5          8          165           166
 link    link       div        script        script
                 .articles
                 .container
                     |
 + - - - + - - - + - + - + - - - + - - - + - - - +
 |       |       |       |       |       |       |
 10      32      54      76      98     120     142
 div     div     div     div     div    div     div  < .article
                      .current                     sibling's  
                          |                          .next()
           +- - - - - - - + - - - - - - - - +
           |                                |
           77                               88
          .item                        .description
           div                              div
            |                                |
  + - - - - + - - - -+           + - - - - - + - - - - -+
  |         |        |           |           |          |
  78        81       84          89          90         94
  div       div      div         div         div        div
                                              |
                                      + - - - + - - - +
                                      |               |
                                      h1              p

The numbers in the Diagram
represent the line-number in the index.HTML file.

So to get to the articles we follow the path
html -> 7-body -> 8-div
(we landed at the PARENT of ALL the Articles)
Those Articles are the CHILDREN to this PARENT.
And the CHILDREN between themselves are SIBLINGS.
And ALL these CHILDREN are carrying the Class article.

In this Diagram i have
put the current Class on the 4th Article...
this would happen if you clicked on the 4th-Article
at wich point you have this article at your fingers via this

$('.article').removeClass('current'); attribute class=current from all those Elements.

$('.description').hide();

$(this).addClass('current'); this as the way to identify this Element, add the Class attribute "current", which via the style.CSS file will cause the change of color via the .current CSS-object,
but from now on if we use the jQuery Selection with the argument '.current'
like $('.current') , we know that we have selected 1 Article-Element, with ALL its CHILDREN

$(this).children('.description').show(); clicked-on Article and ALL its Elements, and from this collection of Elements, choose the Element with the Class "description" set, and show that Element and all its Children.
\==================================
$('.description').show(); Class "description" and show them...you will see all 7 Articles with their description shown.

$('.current').children('.item').hide().children('.description').show()
step 1 , hide the Article-line using the ".item" Class as sub-selection
step 2 , show the Children Elements of the Parent with Class "description"

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

So we have a 76-div which in this diagram has the class attribute current
By using the current-class in the jQuery selector, $(".current")
you will create a jQuery object which has 2 Children
being the 77-div and the 88-div,
these can be targeted by using their ".item" or ".description" class-attribute
$('.current').children('.description').show();

In this diagram you see that the 8-div has 7 Children,
These Children are Siblings to each other,

   8-div - - - - -+
                  | /7-Children/
        .article  + 10-div [first-child]
                  |
        .article  + 32-div    As these div's are
                  |           'siblings' of each-other
                  |           we can use the
                  |           .prev() and .next() methods
                  |                           to navigate
        .article  + 54-div [prev]
                  |
        .article  + 76-div class="current"  - +/2children/
                  |                           + 77-div .item
        .article  + 98-div [next]             |
                  |                           + 88-div .description
        .article  +120-div                    
                  |
        .article  +142-div [last-child]

#3

What a great explanation! Thank you so much.

I was suspecting that "row" and "description" might be two separate classes but then I started thinking about how strings in JavaScript would be all between quotation marks and got confused between JS and HTML/CSS.

Thanks again!