Test Your JavaScript Skills : const keyword

Introduction

Namaste, In this blog I will discuss 10 code scenarios on Javascript const keyword .

Identify the output of the below program
```
 const myval = "Hari";
 const myval =12; 
 console.log(myval);
```
a. error

b.Hari

c.12

d.null

e.undefined

Answer:a

Reason:The const variable cannot be re-declared.
Identify the output of the below program
```
 let myval=10;
 if (myval > 6) {
     const myval2=11;
 }
 console.log(myval2);
```
a.10

b.11

c.error

d.undefined

e.error

Answer:c

Reason:The const variable has block scope.
Identify the output of the below program
```
 console.log("myval3", myval3); 
 const myval3=12;
```
a.12

b.undefined

c.null

d.error

e.nothing

Answer:d

Reason:The const variable is not hoisted
Identify the output of the below program
```
 const obj = {
     no:10
 };
 obj = 100;
 console.log(obj);
```
a.10

b.100

c. {no:10}

d. {obj:100}

e.error

Answer: e

Reason: The const object cannot be updated
Identify the output of the below program
```
 const myval=10;
 myval = "ram";
 console.log(myval)
```
a.10

b.ram

c.error

d.undefined

e.null

Answer:c

Reason:The const variable cannot be re-initialised

Identify the output of the below program

 let myval=10;
 function fx() {
     if (myval > 6) {
         const myval4=8;        
     }
     console.log("myval 4", myval4);
 }
 fx();

a.10

b.8

c.6

d.error

e.undefined

Answer:d

Reason:The const variable has block scope

Identify the output of the below program
```
 const obj = {
     no:10
 };
 obj.no = 200; 
 console.log(obj.no);
```
a.10

b.200

c.undefined

d.error

e.null

Answer:b

Reason:Only the object is constant not it's properties
Identify the output of the below program
```
 const i=10;
 const function fx() {
  i=20;
  return i;
 }
 console.log(fx());
```
a.error

b.10

c.20

d.undefined

e.null

Answer:a

Reason:Function cannot be declared as const
Identify the output of the below program
```
 var i=20;
 const i=10;
 console.log(i);
```
a.10

b.20

c.error

d.no output

e.undefined

Answer:c

Reason:The variable i is already declared hence cannot be re-declared
Identify the output of the below program
```
const obj = {
    no:10,
    name: "Ram"
};
obj.name = "Gopi"; 
console.log(obj.name);
```
a.Gopi

b.Ram

c.10

d.no output

e.error

Answer:a

Reason: The const object properties can be updated