I'm not at all able to understand this exercise


#1


https://www.codecademy.com/en/courses/web-beginner-en-zmn0b/0/5?content_from=make-an-interactive-website%3Ayour-first-program#

I'm not at all able to understand this exercise, can someone explain this code line-by-line..
var main = function(){
$('.icon-menu').click(function(){
$('menu').animate({
left:'0px'
},200);
$('body').animate({
left:'285px'
},200);
});
};
$(document).ready(main);


#2

@mayurnath

+++++ DOM representation of push menu

If your HTML-page is loaded into memory by the Browser
the memory-layout will be build
using the rules, as defined in the Document Object Model
in short the DOM

The DOM representation of the index.html file would look like:

               html
                |
         +------+---------+
         |                |
        head             body
         |                |
    +----+----+      +----+-----------+
    |    |    |      |                |
   link link link  10div(.menu)     27div(.jumbotron)
                    |                 |
     +--------------+----+          29div(.icon-menu)
     |                   |             |
   13div(.icon-close)  18ul          30i (.fa
     |                   |             |  and .fa-bars)
    img       +-----+----++-----+    text  
              |     |     |     |    node
             19li  20li  21li  22li
              |     |     |     |
              a     a     a     a
              |     |     |     |
            text   text  text  text
            node   node  node  node

Now if you look at the DOM representation
the body-Tag is parent to
a 10div Element's Tree ( with class-attribute with class-name "menu" )
and
a 27div Element's Tree ( with class-attr. with class-name "jumbotron" set )

Now if you look in the style.css file,
with which you manage the Display of your Elements,
you will find that
the body object has the property left: 0; being set
( the body-Tree has a _start-Display at position left-0 )_

but
the .menu object has the property left: -285px; being set
and therefor the 10div-Tree is outside of Display.

In your 'app.js' file you are
CREATING a VARIABLE main
to which you assign a so-called anonymous Function
and in the FUNCTION-BODY of this anonymous Function
we are attaching our click Event-handlers
to the HTML-Elements which are
-1 carrying the "icon-menu" class-name as class-attribute
-2 carrying the "icon-close" class-name as class-attribute
( during the assignment the function is NOT executed )

You will have to add the code-line
$(document).ready( main );
which will result in the =main= Function to be executed
AFTER the Browser has set the ready Event-flag.

++++++++++ structure P u s h M e n u function
The structure of your =main= Function should look like....

  var main= function() {
     $('.icon-menu').click( function() {
           //Your animation
     });

     $('.icon-close').click( function() {
           //Your animation
      });
   };
 $(document).ready(main);

explanation of the push-menu setup
https://www.codecademy.com/forum_questions/55b3d3c1d3292f529b00005e

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

what is CSS explained site:developer.mozilla.org
https://developer.mozilla.org/en-US/docs/Web/CSS/Syntax
https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started/What_is_CSS
https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity

http://stackoverflow.com/questions/1795438/load-and-execution-sequence-of-a-web-page