basic of javascript lesson 1

DATA TYPES IN JAVASCRIPT

JAVASCRIPT MAINLY HAVE 5 TYPES OF DATA TYPES 

1. STRING LIKE- 

    VAR USENAME="MANISH CHAUHAN"; USERNAME IS 

    MANISH CHAUHAN NOW

2. NUMBER

    LIKE-VAR X=200; X CONTAIN 200.

3. OBJECT IS USED TO STORE COMPLEX VALUES IN JAVASCRIPT THERE ARE MULTIPLE WAYS YOU CAN CREATE A OBJECT IS JAVASCRIPT SO BELOW ARE THE EXAMPLE.

    //object

 var obj={

  name:"manish",

  age:35

}

var obj1=new Object();

obj1.name="manish";

obj1.age=22;

var obj2=Object.create(null,{

      'userName': {

  value: "manish", 

  writable: true, 

  enumerable: true

      },

       'age': {

  value: 35, 

  writable: true, 

  enumerable: true

      }

      });

4. DATE 

    

    var date=new Date();

5. ARRAY

    

    var myArray=[];

var myArray1=new Array();

ONE THING IS THAT YOU CAN STORE ALL TYPES OF ITEMS IN SAME ARRAY LIKE

VAR MYARRAY=[1,2,3,"A,"B"];

THE REASON BECAUSE JAVASCRIPT IS NOT A STRICT TYPE CHECKED LANGUAGE SO YOU CAN ALTER THE BEHAVIOUR OF A VARIABLE AT RUNTIME. FOR EXAMPLE

VAR USERNAME="MANISH";

LATER ON YOU CAN CHANGE IT TO USERNAME=222; SO THIS BEHAVIOUR CAN EASILY BRING LOTS OF BUGS WHEN YOUR PROJECT IS BIG.

2. JavaScript Hoisting is another important part of javascript

    Hoisting is JavaScript's default behavior of moving declarations to the top.

     

    what do you mean by above line 

    so let's check out this

       //in this case you would get a error 

      //Error: myNumber is not defined

      console.log(myNumber)

   the above behaviour is right because myNumber is not defined yet

    but if you declare a variable later on the behaviour would be like below

    

console.log(myNumber)

var myNumber; 

the value of myNumber would be undefined because javascript moves everything to the top so for compiler the statement would be like 

var myNumber; 

console.log(myNumber)

   

next coming soon.....