Test your JavaScript Skills: Fundamentals-14

Introduction

Namaste, In this blog I will discuss 7 code scenarios on Javascript fundamentals.

1. Identify the output of the below program

    const i=10;
    let j=20;
    const i=30;
    console.log("value", i);
   

   a.30

   b.10

   c.20

   d. error

   e.undefined

   Answer: d

   Reason: The 'const' variable cannot be re-declared.

2. Identify the output of the below program

    let k=20;
    if (k>10) {
        const a=4;
    }
   
    console.log("value", a);
   

   a.20

   b.4

   c.undefined

   d. null

   e.error

   Answer: e

   Reason: The 'const' has a block scope and hence cannot be accessed outside the block.

3. Identify the output of the below program

   
    const obj = {
        empno:10,
        empname:"ram"
    };
   
    obj.empno = 50;
    console.log("value", obj);
   

   a.error

   b.{empno:10, empname:"ram"}

   c.{empno:50, empname:"ram"}

   d. undefined

   e.{empno:50}

   Answer: c

   Reason: The obj is 'const', not it's properties.

4. Identify the output of the below program

    function fx() {
        const i=10;
        function fx2() {
            console.log("value", i); 
        }
        fx2();
    }
   
    fx();
   

   a.10

   b.error

   c.undefined

   d. null

   e.0

   Answer: a

   Reason: In the given context the variable i is global to fx2 function hence accessible inside it.

5. Identify the output of the below program

    try {
        const i=2;
    }catch(e) {
        console.log("error",e);
    }
    console.log("value",i);
   

   a. 2

   b.error

   c.0

   d. undefined

   e.null

   Answer: b

   Reason: The 'const' has a block scope.

6. Identify the output of the below program

    console.log("value", a); 
    const a=10;
   

   a.10

   b.undefined

   c.error

   d. null

   e.0

   Answer: c

   Reason: The 'const' is not hoisted hence the error.

7. Identify the output of the below program

    const obj2  = function () {}
    obj2.i = 30;
    console.log("value", obj2.i);
   

   a.function(){}

   b.30

   c.error

   d. undefined

   e.null

   Answer: b

   Reason: The object obj2 is const, not its properties.