Obify Consulting

• Its a mechanism where variables and functions declaration to the top of the scope.

• It’s a mechanism where variables and function declaration are moved to the top of the scope.

• Null :- We assign value NULL, it indicates absence of data.
• Undefined :-  Variable has been created but value is not assigned.

• Null indicates intentional absence of data. Null indicates its not ZERO, its not empty its just absence of data.
• <script>

    var y = 10;

    var z = “Shiv”;

    var x;

    var emptystring = “”;

    var zero = 0;

    var n = null;

  </script>

• Undefined means the variable has been declared but no value is assigned to it.
• Example:-

• There are 8 types of data type. And it is divided into two parts.
• 1.Primitive 2.Objects
• Primitive – string, number, null, undefined, boole, big int, symbol.
• Objects – object.

• JavaScripts determines data types depending on the value assigned.

<Script>

var x=100;

var watisdatatype = typeof(x);

x=true;

waitsdatatype = typeof(x);

<Script>

• JavaScript is a dynamic language means data types of the variables can change during the run time.

<script>

var x=0;

x++;

x = “Text1”;

x = true;

</script>