Front End Technology Articles - Page 380 of 860

Suppose we have a sorted array of literals like this −const arr = [2, 2, 3, 3, 3, 5, 5, 6, 7, 8, 9];We are required to write a JavaScript function that takes in one such array and returns the first number that appears only once in the array.If there is no such number in the array, we should return false.For this array, the output should be 6.ExampleThe code for this will be −const arr = [2, 2, 3, 3, 3, 5, 5, 6, 7, 8, 9]; const firstNonDuplicate = arr => {    let appeared = false;   ... Read More

We are required to write a JavaScript function that takes in a Number, say n, and we are required to check whether there exist such three consecutive natural numbers (not decimal/floating point) whose sum equals to n.If there exist such numbers, our function should return them, otherwise it should return false.ExampleThe code for this will be −const sum = 54; const threeConsecutiveSum = sum => {    if(sum < 6 || sum % 3 !== 0){       return false;    }    // three numbers will be of the form:    // x + x + 1 + ... Read More

We are required to write a JavaScript function that takes in a lowercase string and sorts it in the reverse order i.e., b should come before a, c before b and so on.For example:If the input string is −const str = "hello";Then the output should be −const output = "ollhe";The code for this will be −const string = 'hello'; const sorter = (a, b) => {    const legend = [-1, 0, 1];    return legend[+(a < b)]; } const reverseSort = str => {    const strArr = str.split("");    return strArr    .sort(sorter)    .join(""); }; console.log(reverseSort(string));Following is the output on console −ollhe

We have an array of numbers like this −const arr = [1, 1, 5, 2, -4, 6, 10];We are required to write a function that returns a new array, of the same size but with each element being the sum of all elements until that point.Therefore, the output should look like −const output = [1, 2, 7, 9, 5, 11, 21];Therefore, let’s write the function partialSum(), The full code for this function will be −const arr = [1, 1, 5, 2, -4, 6, 10]; const partialSum = (arr) => {    const output = [];    arr.forEach((num, index) => { ... Read More

We are required to create a function that takes in a number and finds the sum of its digits recursively until the sum is a one-digit number.For examplefindSum(12345) = 1+2+3+4+5 = 15 = 1+5 = 6Therefore, the output should be 6.Let’s write the code for this function findSum()// using recursion const findSum = (num) => {    if(num < 10){       return num;    }    const lastDigit = num % 10;    const remainingNum = Math.floor(num / 10);    return findSum(lastDigit + findSum(remainingNum)); } console.log(findSum(2568));We check if the number is less than 10, it’s already minified and ... Read More

We are required to write a JavaScript function that takes in an array of literals. Our function should return a new array with all the triplets filtered.The code for this will be −const arr1 = [1, 1, 1, 3, 3, 5]; const arr2 = [1, 1, 1, 1, 3, 3, 5]; const arr3 = [1, 1, 1, 3, 3, 3]; const arr4 = [1, 1, 1, 1, 3, 3, 3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 7, 7]; const removeTriplets = arr => {    const hashMap = arr => arr.reduce((acc, val) => { ... Read More

We have a parentArray that contains many sub arrays each of the same size, each sub array is an array of objects containing two properties: key and value. Within a subarray it is confirmed that two objects cannot have the same key but all subarrays have the same pair of n keys where n is the size of the sub array.Our job is to prepare an object with key as key of objects and value being an array that contains all the values for that particular key.Here is a sample parent array −const parentArray = [[ {    key: 123, ... Read More

We have an object with other objects being its property value, it is nested to 2-3 levels or even more.Here is the sample object −const people = {    Ram: {       fullName: 'Ram Kumar',       details: {          age: 31,          isEmployed: true       }    },    Sourav: {       fullName: 'Sourav Singh',       details: {          age: 22,          isEmployed: false       }    },    Jay: {       fullName: 'Jay ... Read More

We have an array of objects that contains data about some cars. The array is given as follows −const cars = [{    company: 'Honda',    type: 'SUV' }, {    company: 'Hyundai',    type: 'Sedan' }, {    company: 'Suzuki',    type: 'Sedan' }, {    company: 'Audi',    type: 'Coupe' }, {    company: 'Tata',    type: 'SUV' }, {    company: 'Morris Garage',    type: 'Hatchback' }, {    company: 'Honda',    type: 'SUV' }, {    company: 'Tata',    type: 'Sedan' }, {    company: 'Honda',    type: 'Hatchback' }];We are required to write a program ... Read More

We need to write a function that reads a string and converts the odd indexed characters in the string to upperCase and the even ones to lowerCase and returns a new string.Full code for doing the same will be −const text = 'Hello world, it is so nice to be alive.'; const changeCase = (str) => {    const newStr = str    .split("")    .map((word, index) => {       if(index % 2 === 0){          return word.toLowerCase();       }else{          return word.toUpperCase();       }    })   ... Read More