explain javascript code

I downloaded sample code - .html file and i am trying to understand it..

Within <head></head> this code of javascript is written....
 <script>
 
      require([
        "esri/map", "esri/layers/ArcGISTiledMapServiceLayer",
        "esri/domUtils", "esri/request",
        "dojo/parser", "dojo/number", "dojo/json", "dojo/dom",
        "dijit/registry", "modules/RasterLayer",

        "dijit/layout/BorderContainer", "dijit/layout/ContentPane",
        "dijit/form/HorizontalSlider", "dojo/domReady!"
      ], function(
        Map, ArcGISTiledMapServiceLayer,
        domUtils, esriRequest,
        parser, number, JSON, dom,
        registry, RasterLayer
      ) {

        //some code
        function mapLoaded() {
//code of maploaded
        }

        function getRasterData() {
       //code
        }

        function setElevation() {
        //code
         }
 
         function supports_canvas() {
                //code
         }
      });
    </script>

Can you please help me understand what it is ?

thanks so much
ts84zsAsked:
Who is Participating?
 
Darrell PorterConnect With a Mentor Enterprise Business Process ArchitectCommented:
Essentially, this is JavaScript supporting ArcGIS Server calls.

The "require" function allows modules to be dynamically loaded as needed and specifies what is needed to get them.
See http://www.sitepoint.com/understanding-requirejs-for-effective-javascript-module-loading/ for a very detailed explanation of the "require" function call.

If you would like a detailed explanation of the other ArcGIS JavaScript calls, I would highly recommend looking at
https://developers.arcgis.com/javascript/jshelp/
which explains the various functions and how to use them.
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GaryConnect With a Mentor Commented:
Did you read thru
https://developers.arcgis.com/javascript/jstutorials/#step1

Load required modules from the api and set up the required functions is basically all it is doing.
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ts84zsAuthor Commented:
But i have not used dojo type of javascript ... so i do not understand the exact javascript  code

Is it executing that function when the page is loaded ?
function(
        Map, ArcGISTiledMapServiceLayer,
        domUtils, esriRequest,
        parser, number, JSON, dom,
        registry, RasterLayer
      ) { //code -mycode }

so mycode section will be executed when the html page will be loaded ?
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Darrell PorterEnterprise Business Process ArchitectCommented:
It is LOADING that code into the browser and instantiating the instances of those calls.  If you are performing code or function calls in the header, they will be executed on page load.  Otherwise, the code won't actually run until it's called.
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ts84zsAuthor Commented:
function(
        Map, ArcGISTiledMapServiceLayer,
        domUtils, esriRequest,
        parser, number, JSON, dom,
        registry, RasterLayer
      ) { //code -mycode }



so if i have alert('mymessage' )  ; in mycode section of that code, it will be executed when the page is loaded since it is within <script></script> ?
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ts84zsAuthor Commented:
sorry please ignore my previous comment...

i got to know it now...

thanks
0
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