index.js

// variable

// let keyword
let intValue = 10;
console.log(intValue);

// Exception case
//console.log(intValue1);   Cannot access 'intValue1' before initialization
 //let intValue1= 20;




//var keyword  
 var intValue2 = 25;
 console.log(intValue2);

//var intValue = 20;
//console.log(intValue); // Identifier 'intValue' has already been declared

 intValue2 = 30; // once initialized var, it has scope throughout file.
 console.log(intValue2);

// exception case
 console.log(intValue3); // in output we get undefined
 var intValue3 =40;
  

// const keyword
// one time declaration. It's value remains same throughout program.
 const pi = 3.14;
 console.log(pi);

//exception case
// pi = 4.5;
// console.log(pi); // Assignment to constant variable.


//console.log(int);  //Cannot access 'int' before initialization
//const int = 3;