Test your JavaScript Skills: Fundamentals - 15

Introduction

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

1. Identify the output of the below program

    if 4>3 
        console.log("test");
   

   a.test

   b.undefined

   c.no output

   d.null

   e.error

   Answer: e

   Reason: The expression 4>3 should be in braces ().

2. Identify the output of the below program

    if (4>3) console.log("true") else console.log("false");
   

   a.true

   b.false

   c.undefined

   d.error

   e.no output

   Answer: d

   Reason: The syntax is incorrect. The semicolon is missing for the first truthy instruction i.e. console.log("true");

3. Identify the output of the below program

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

   a.true

   b.false

   c.undefined

   d.error

   e.0

   Answer: a

   Reason: Here 'true' is coerced to 1 and null is coerced to 0 hence 1+0 is 1.

4. Identify the output of the below program

    if (4>3) console.log("true"); else console.log("false");
   

   a.true

   b.false

   c.undefined

   d.error

   e.null

   Answer: a

   Reason: The condition is true hence result is true.

5. Identify the output of the below program

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

   a.NaN

   b.true

   c.false

   d.undefined

   e.error

   Answer: c

   Reason: Here 'undefined' is coerced into NaN and true to 1 hence NaN+1 is NaN

6. Identify the output of the below program

    if ({no:10}+ undefined)    
        console.log("true");
    else
        console.log("false");
   

   a.undefined

   b.false

   c.error

   d.true

   e.null

   Answer:d

   Reason: The object is converted to a string and undefined is concatenated to a string.

7. Identify the output of the below program

    if (4>3) console.log("true");
   

   a.true

   b.no output

   c.false

   d.error

   e.undefined

   Answer: a

   Reason: Condition is true hence result is true.