Javascript

Javascript interview questions

1) create a function to  reverse a string without using the built-in reverse() method.  

Ans 1)

function reverseString(str) { 

  let reversed = ‘’; 

  for (let i = str.length – 1; i >= 0; i–) { 

    reversed += str[i];

  } 

  return reversed; 

} 

2) write a function to find the largest and smallest numbers in the array

a = [33,22,44,55,222,444,8]

    temp= a[0];

    for(i=1;i

        if(temp < a[i]){

            temp = a[i]

        }

    }

    console.log(temp)

3) what is an array and how it is different from json

4) difference between let and const

5) what is promises Explain with examples

6) write a  function that removes duplicates from an array, keeping only the unique elements

Write a program to convert from camel case to kebab case?

9. We need to Fill the color in div like one Red and second blue and continue like this.

 

 

 

 

 

 

 

 

10.we need to fetch the data for 3rd div using JavaScript.

11.Function to remove first word from a string

Ans 11

function removeFirstWord() {

  //let str = 'Hello World';

    let str = 'public\dr1.jpg'

  //let result = str.substr(str.indexOf(' ')+1);

    let result = str.substr(str.indexOf('c')+1);

    return result;

}

removeFirstWord();

12 How to find length of an array with out using .length method

let myarray = [10,20,30,40,50,60,70,80]

const mylengthfunction = (myarray)=>{

    for(i=0;;i++){

        if(myarray[i]== undefined){

            break;

        }

    }

    return i

}

var length = mylengthfunction(myarray)

Ans 2)

 

8) How to find the middle value index of let x =[22,80,34,80,80,11,55,80,80]

Ans 8

let a=[20,80,40,80,60,80,34,80,66,80,22,67,80,22,80]

i=0;

for(x in a){

    //console.log(x)

    if(a[x] == 80){

       //console.log(x)

       i++

    }

}

 if(i%2==0){

    checkmiddlevalue = false

}else{

    checkmiddlevalue = true

}

if(checkmiddlevalue == true){

        var middlevalue = (i/2)+.5;

        //console.log(middlevalue)

        j=0;

        for(x in a){

            //console.log(x)

            if(a[x] == 80){

            //console.log(x)

            ++j;

            if(j == middlevalue){

                    console.log(x)

                    break;

            }            

            }

        }

}else{

    console.log("cannot find middle value ")

}

12) JavaScript Program to Remove Non-Alphanumeric Characters from a String

13) Bubble sort Implementation using JavaScript

function bubbleSort(arr) {

    for (var i = 0; i < arr.length; i++) {

        for (var j = 0; j < (arr.length - i - 1); j++) {

            if (arr[j] > arr[j + 1]) {

                var temp = arr[j]

                arr[j] = arr[j + 1]

                arr[j + 1] = temp

            }

        }

    }

 

    // Print the sorted array

    console.log(arr);

}

 

// This is our unsorted array

var arr = [234, 43, 55, 63, 5, 6, 235, 547];

// Now pass this array to the bblSort() function

bblSort(arr);

14) how to reverse an array elements

Ans 

let x= [121,31,141,251,61];

let y = [];

let count = 0;

for(i=x.length-1;i>=0;i--){

    y[count] = x[i];

    count++;

}

console.log(x)

console.log(y)

7) create a  function that finds the second smallest element in an array of integers. 

15) How to get all matched value index in an string

let myarray = [10,40,20,30,40,50,40,60,40,70,40,60];

count = 0;

allmatchedelements = ""

for(i=0;i

    if(myarray[i] == 40){

       // console.log(i)

        allmatchedelements = allmatchedelements+i+' ';

        count++;

    }

}

console.log(allmatchedelements)

16) Sorting algorithm

let x = [211,45,2,9,666,23]

//console.log(x);

// if(x[0]>x[1]){

//     temp = x[0];

//     x[0] = x[1];

//     x[1] = temp;

// }

console.log(x);

for(i=x.length-1;i>=0;i--){

    for(j=0;j<=i;j++){

        if(x[j]>x[j+1]){

            temp = x[j];

            x[j] = x[j+1];

            x[j+1] = temp;

        }

    }

}

console.log(x);

17) given a string let mystring =”Hello how are you hello there and hello world”

Count the number of hello word repeated in an string

Ans 

let newmystringarray = mystring.split(' ')

console.log(newmystringarray)

count = 0;

for(i=0;i<=newmystringarray.length; i++){

    if(newmystringarray[i] == 'hello'){

        count++;

    }

}

console.log(count)