Object Literals

• lets say i have hospital and i have n number of employees working there.
• and each employee has name, job title, salarly, department.
• if i want to represt that programmatically,i would create variable for each one of these, and I have n numbers of employees, so i am going to heavily repeat each value n number of times.
• it’s like banging my head on wall.

how to solve this problem ?

• there is a concept in programming called object.
• object literals is complex datatype in javascript.
• object consist of attributes.
• attributes come in key=value pair.
• attributes can be primitve (numbers, strings,boolean) datatype, arrays or functions datatype.

Why objects are useful ?

• objects are effective because it help me create less repititve code.
• it group related data in accessable way.

how to define objects ?

• var objName = { key: value, key2:val2, functionKey: function(){ code .... } }

• example: var employeeAhmad = { name: 'ahmad', jobTitle: doctor salary : 800, department: 'ICU' }

how to access attributes and modify it ?

* access attributes
  * objectName.attributeName
     * example : employeeAhmad.name;
* modify attributes.
  * objectName.attributeName = 'new value';
     * example : employeeAhmad.name = 'Afaf';

The Document Object Model (DOM):

• Specifies how browsers should create a model of an HTML page.
• How JavaScript can access and update the objects of the page while it is in the browser window.
• The DOM is neither part of HTML, nor part of JavaScript; it is a separate set of rules. It covers two primary areas:
  • Create the HTML page object tree:
    • When the browser loads a web page, it creates a model of the page in memory.
    • The DOM specifies the way in which the browser should structure this model using a** DOM tree**.
  • How to access and modify objects :
    • defines methods and properties to access and update each object in this model.
    • Application Programming Interface (API). User interfaces let humans interact with programs.

      THE DOM TREE IS A MODEL OF A WEB PAGE

      As I mentioned earlier, The DOM structure model of objects, it consist of elements of the webpage and store it in the memory, it’s called the DOM tree. Example of DOM TREE :

• it consist of four parts:
  • THE DOCUMENT NODE