47BlokVSfuncScope.js

//   Block Scope vs Function Scope

//  'let' and 'const' are block scope.

// 'let' and 'const' are Accessable in the same Block.
// 'let' and 'const' are mostly use.

// block #1
{
    let firstName = "abhishek";
    console.log(firstName);
}

// block #2
{
    const firstName = "prithvi";
    console.log(firstName);
}


// 'var' is function scope.
// 'var' is accessable from outside of the block.
// "var" is global scope we can acssec it all over code(main function)
{
    var firstName = "singh";
}
console.log(firstName);


// use of Block Scope

//  #01
//  if(ture){
//      let firstName = "Abhishek";
//      console.log(firstName);
//  }
//  console.log(firstName);  // these will generate error.

//  #02
// if(true){
//     var firstName1 = "Abhishek";
//     console.log(firstName1);
// }
// console.log(firstName1);

// #03 using 'let' & 'const' 
function myApp(){
    if(true){
        let firstName1 = "Abhishek";
        console.log(firstName1);
    }
    if(true){
        console.log(firstName1);
    }
    console.log(firstName1);  
}
myApp();

// #04  useing 'var'
// function myApp(){
//     if(true){
//         var firstName1 = "Abhishek";
//         console.log(firstName1);
//     }
//     if(true){
//         console.log(firstName1);
//     }
//     console.log(firstName1);  
// }
// myApp();