Test Your JavaScript Skills:Fundamentals-16

Introduction

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

1. Identify the output of the below program

    console.log({no:100} + null );
   

   a.error

   b.{no:100}0

   c.{no:100}1

   d.{no:100}null

   e.[object Object]null

   Answer: e

   Reason: The object is converted to a string which is concatenated with null.

2. Identify the output of the below program

    var i=10;
    let i=30;
    console.log("value",i);
   

   a.10

   b.30

   c.error

   d.undefined

   e.null

   Answer: c

   Reason: There is an error because of re-declaration.

3. Identify the output of the below program

    var k=10;
    const k=20;
    console.log("value", k);
   

   a.null

   b.20

   c.10

   d.undefined

   e.error

   Answer:e

   Reason: There is an error because of re-declaration.

4. Identify the output of the below program

    if ("ram"+undefined)   
        console.log("true");
    else
        console.log("false");
   

   a.true

   b.false

   c.undefined

   d.null

   e.error

   Answer: a

   Reason: The string is concatenated with undefined hence condition is true.

5. Identify the output of the below program

    console.log({no:10} + {name:"ram"});
   

   a. error

   b.true

   c.[no:10] [name: "ram"]

   d.[object Object] [object Object]

   e.{no:10} {name:"ram"}

   Answer: d

   Reason: Both objects are converted to a string and concatenated.

6. Identify the output of the below program

    let j=10;
    var j=30;
    console.log("value",j);
   

   a.30

   b.10

   c.undefined

   d.null

   e.error

   Answer: e

   Reason: There is an error because of re-declaration.

7. Identify the output of the below program

    console.log({no:10});
   

   a.[object Object]

   b.error

   c.{no:10}

   d.undefined

   e.object

   Answer: c

   Reason: The object is displayed as it is.