Test Your JavaScript Skills : let Keyword - 29

Introduction

Namaste, In this blog I will discuss 7 code scenarios on Javascript 'let' keyword.

1. Identify the output of the below program

    console.log ("myval2", myval2); 
    let myval2=101;
   

   a.101

   b.null

   c.error

   d.undefined

   e.no output

   Answer:c

   Reason:The let variables are not hoisted

2. Identify the output of the below program

    for (let a=10;a<11;) {
        a++;
    }
    console.log(a);
   

   a.10

   b.11

   c.undefined

   d.error

   e.no output

   Answer:d

   Reason:The let keyword has block scope

3. Identify the output of the below program

    let i=11;
    if ( i > 9){
        let c = 13;
    }
    console.log("c:", c);
   

   a.11

   b.13

   c.no output

   d.undefined

   e.error

   Answer:e

   Reason:The let keyword has block scope

4. Identify the output of the below program

    function fx() {
        let myval3=200;
        console.log ("myval4", myval4); 
        let myval4=201;
    }
    fx();
   

   a.200

   b.201

   c.error

   d.undefined

   e.no output

   Answer:c

   Reason:The let variables are not hoisted

5. Identify the output of the below program

    let myval5=30;
    let myval5=40; 
    console.log(myval5)
   

   a.30

   b.40

   c.error

   d.undefined

   e.null

   Answer:c

   Reason:The let variable cannot be re-declared

6. Identify the output of the below program

    // Block scope inside function
    function fx2() {
        try {
            let d=20;
        }catch(e) {
            console.log("error"); 
        }
        console.log(d);
    }
    fx2();
   

   a. 20

   b.error

   c.no output

   d.11

   e.undefined

   Answer:b

   Reason:The let variable has block scope

7. Identify the output of the below program

    let a=10;
    const a=20;
    console.log(a);
   

   a.10

   b.20

   c.no-output

   d.error

   e.undefined

   Answer:d

   Reason: A variable once declared using let cannot be re-declared.