Introduction

Namaste, In the post I will discuss 7 FAQs on Javascript fundamentals

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1. Identify the output of the below program

    let mydata = NaN/2;
    console.log("mydata", mydata);
   

   a. Error

   b. NaN

   c. Undefined

   d. 100.5

   e. null

   Answer: b

   Reason: NaN when divided is still Not a Number.

2. Identify the output of the below program

    let mydata = 1/0;
    console.log("mydata", mydata);
   

   a. 1

   b. Error

   c. 0

   d. Infinity

   e. NaN

   Answer: d

   Reason: In Javascript a non-zero number divided by 0 is infinity.

3. Identify the output of the below program

    let mydata = 0/0;
    console.log("mydata", mydata);
   

   a. 3

   b. 0

   c. Error

   d. null

   e. NaN

   Answer: e

   Reason: Zero divided by 0 is NaN.

4. Identify the output of the below program

    let mydata = undefined;
    console.log("type", typeof mydata);
   

   a. error

   b. null

   c. object

   d. undefined

   e.number

   Answer: d

   Reason: A variable containing undefined as a value is an undefined type.

   Undefined is 1 of the 7 primitives.

5. Identify the output of the below program

    let mydata = NaN * 2;
    console.log("mydata", mydata);
   

   a. null

   b. undefined

   c. NaN

   d. Error

   e.false

   Answer: c

   Reason: NaN when multiplied by a number is still Not a Number.

6. Identify the output of the below program

    let mydata = 0/3;
    console.log("mydata", mydata);
   

   a. 0

   b. 3

   c. Error

   d. NaN

   e.undefined

   Answer: a

   Reason: Zero divided by any number (except for 0) is 0.

7. Identify the output of the below program

    let mydata = NaN + 2;
    console.log("type", typeof mydata);
   

   a. boolean

   b. number

   c. NaN

   d. Error

   e.string

   Answer: b

   Reason: NaN is a number type.

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