Test Your JavaScript Skills : ES8 (JavaScript 2017) - 45

Introduction

Namaste, In this blog I will discuss 10 code scenarios on Javascript .

1. Identify the output of the below program

    function fx() {
        return new Promise(resolve => {
          setTimeout(() => {
            resolve('resolved');
          }, 1000);
        });
      }
   
      async function asyncFx() {    
        const result = await fx();
        console.log(result); 
      }
   
      asyncFx();
   

   a.resolved

   b.reject

   c.undefined

   d.error

   e.null

   Answer:a

   Reason:The promise is successfully completed.

2. Identify the output of the below program

    function fx() {
        return new Promise((resolve,reject) => {
          setTimeout(() => {
            reject('resolved');
          }, 1000);
        });
      }
   
      async function asyncFx() {    
        const result = await fx();
        console.log(result); 
      }
   
      asyncFx();
   

   a.reject

   b.error

   c.resolve

   d.undefined

   e.null

   Answer:b

   Reason:The program gives an error.

3. Identify the output of the below program

   
    async function getData() {
        try {
            let response = await  fetch("jsontest.com/key/value");
            let data = await response.json();
            console.log(data);
        }catch (err) {
                console.log("problem");
         }
    }
    getData();
   

   a.problem

   b.{key:value}

   c.json

   d.undefined

   e.null

   Answer:a

   Reason:The incorrect url yields into an error.

4. Identify the output of the below program

    let city = {
        "delhi":1000,    
      };
      console.log(Object.entries(city));
   

   a. [ 'delhi', 1000 ]

   b. { 'delhi', 1000 }

   c. error

   d. [ [ 'delhi', 1000 ] ]

   e. 'delhi', 1000

   Answer:d

   Reason:The output is [ [ 'delhi', 1000 ] ].

5. Identify the output of the below program

   
    let city = {
        "delhi":1000,  
      };
   
      for (let [k,v] of Object.entries(city))
        console.log(k,v);
   

   a.[ 'delhi', 1000 ]

   b. { 'delhi', 1000 }

   c. error

   d. [ [ 'delhi', 1000 ] ]

   e. 'delhi', 1000

   Answer:e

   Reason:Individual values are extracted and printed.

6. Identify the output of the below program

    let city = {    
        "mumbai":2000,
        "bangalore":1500
      };
   
    console.log(Object.values(city));
   

   a.[2000,1500]

   b.[2000]

   c.[1500]

   d.[mumbai:2000]

   e.[bangalore:1500]

   Answer:a

   Reason:The values() function only extracts the values.

7. Identify the output of the below program

    let city = {    
        "mumbai":2000,
        "bangalore":1500
      };
   
      let sum=0;
    for (let obj of Object.values(city)) {
       sum = obj + sum;
    }
    console.log(sum);
   

   a.error

   b.undefined

   c.3500

   d.2000

   e.1500

   Answer:c

   Reason:The values are summed up.

8. Identify the output of the below program

    let city = {
        "delhi":1000,
     };
    let obj = Object.getOwnPropertyDescriptors(city);
    console.log(obj.delhi.enumerable);
   

   a.true

   b.false

   c.delhi

   d.1000

   e.error

   Answer:a

   Reason:The enumerable is true by default.

9. Identify the output of the below program

   
    async function getData() {
        try {
            let response = await  fetch("http://echo.jsontest.com/key/value");
            let data = await response.json();
            console.log(data);
        }catch (err) {
                console.log("error ");
         }
    }
   
    getData();
   

   a.{key:value}

   b.error

   c.echo

   d.undefined

   e.10

   Answer:a

   Reason:The value returned is {key:value}.

10. Identify the output of the below program

    function fx() {
        return new Promise((resolve,reject) => {
          setTimeout(() => {
            reject('resolved');
          }, 1000);
        });
      }
    
      async function asyncFx() {    
        try {
        const result = await fx();
        }catch (err) {
          console.log(err); 
        }
      }
    
      asyncFx();
    

    a.resolved

    b.reject

    c.error

    d.undefined

    e.null

    Answer:a

    Reason:When error occurs catch block is called and prints resolved.