ProblemWe are required to write a JavaScript function that takes in a number n. Our function should count and return the number of times we will have to use 9 while counting from 0 to n.ExampleFollowing is the code − Live Democonst num = 100; const countNine = (num = 0) => {    const countChar = (str = '', char = '') => {       return str       .split('')       .reduce((acc, val) => {          if(val === char){             acc++;          };          return acc;       }, 0);    };    let count = 0;    for(let i = 0; i

ProblemWe are required to write a JavaScript function that takes in a positive integer n written as abcd... (a, b, c, d... being digits) and a positive integer pwe want to find a positive integer k, if it exists, such as the sum of the digits of n taken to the successive powers of p is equal to k * n.In other words −Is there an integer k such as : (a ^ p + b ^ (p+1) + c ^(p+2) + d ^ (p+3) + ...) = n * kIf it is the case, we will return k, if ... Read More

ProblemWe are required to write a JavaScript function that takes in an array that represents the floor numbers at which a building lift stopped during an interval of time.From that data, our function should return the count of total number of floors covered by the lift in that time.ExampleFollowing is the code − Live Democonst arr = [7, 1, 7, 1]; const floorsCovered = (arr = []) => {    let res = 0;    for (let i = 0; i < arr.length; i++){       if (arr[i] > arr[i+1]){          res += arr[i] - arr[i+1];   ... Read More

ProblemWe are required to write a JavaScript function that takes in a decrypted message and returns its source message.All we know is the algorithm used to encrypt that message.And the algorithm is −Reverse the message string.Replace every letter with its ASCII code in quotes (A to '65', h to '104' and so on).Insert digits and spaces as is.ExampleFollowing is the code − Live Democonst str = '12 hello world 30'; const decryptString = (str = '') => {    const alpha = 'abcdefghijklmnopqrstuvwxyz';    let res = '';    for(let i = str.length - 1; i >= 0; i--){     ... Read More

ProblemWe are required to write a JavaScript function that takes in an array of exactly two subarrays with two numbers each.Both the subarrays represent a rational number in fractional form. Our function should add the rational numbers and return a new array of two numbers representing the simplest form of the added rational number.ExampleFollowing is the code − Live Democonst arr = [    [1, 2],    [1, 3] ]; const findSum = (arr = []) => {    const hcf = (a, b) => b ? hcf(b, a % b) : a;    if(!arr.length){       return null;   ... Read More

ProblemWe are required to write a JavaScript function that takes in an array of numbers arr, and a number n.Our function should retrieve the n smallest from the array arr without disturbing their relative order. It means they should not be arranged in increasing or decreasing order rather they should hold their original order.ExampleFollowing is the code − Live Democonst arr = [6, 3, 4, 1, 2]; const num = 3; const smallestInOrder = (arr = [], num) => {    if(arr.length < num){       return arr;    };    const copy = arr.slice();    copy.sort((a, b) => a ... Read More

ProblemWe are required to write a JavaScript function that takes in a string and replaces all occurrences of the vowels in the string with their index in the string (1-based).It means if the second letter of the string is a vowel, it should be replaced by 2.ExampleFollowing is the code − Live Democonst str = 'cancotainsomevowels'; const replaceVowels = (str = '') => {    const vowels = 'aeiou';    let res = '';    for(let i = 0; i < str.length; i++){       const el = str[i];       if(vowels.includes(el)){            res += ... Read More

ProblemWe are required to write a JavaScript function that takes in two strings, str1 and str2. Our function should return true if a portion of str1 characters can be rearranged to match str2, otherwise returns false.ExampleFollowing is the code − Live Democonst str1 = 'rkqodlw'; const str2 = 'world'; const canForm = (str1 = '', str2 = '') => {    if(str1.length < str2.length){       return false;    };    const res = str2.split('');    str1.split("").forEach(val => {       if(res.includes(val)){          res.splice(res.indexOf(val), 1);       };    });    return res.length === 0; }; console.log(canForm(str1, str2));OutputFollowing is the console output −true

ProblemWe are required to write a JavaScript function that takes in a number that represents a year and find the century that year falls in.For instance,1864 falls in the 19th century.2021 falls in the 21st century.ExampleFollowing is the code − Live Democonst year = 1956; const findCentury = (year) => {    let century = 0;    for(let i = 0; i < year; i++){       if(i % 100 === 0){          century++;       };    };    return century; }; console.log(findCentury(year));OutputFollowing is the console output −20

ProblemWe are required to write a JavaScript function that takes in a string of words str. Our function needs to return an array of the words, sorted alphabetically by the final character in each.If two words have the same last letter, the returned array should show them in the order they appeared in the given string.ExampleFollowing is the code − Live Democonst str = 'this is some sample string'; const sortByLast = (str = '') => {    const arr = str.split(' ');    const sorter = (a, b) => {         return a[a.length - 1].charCodeAt(0) - b[b.length ... Read More