We are required to illustrate the correct way to check whether a particular key exists in an object or not. Before moving on to the correct way let's first examine an incorrect way and see how actually its incorrect.Way 1: Checking for undefined value (incorrect way)Due to the volatile nature of JavaScript, we might want to check for the existence of key in an object like this −const obj = { name: 'Rahul' };if(!obj['fName']){}orif(obj['fName'] === undefined){}These both are incorrect ways. Why?Because in this case there happens to be no 'fName' key, but suppose there existed a 'fName' which was deliberately ... Read More

We are required to write a JavaScript function that takes in an array of numbers. Our function should return true if the difference between all adjacent elements is the same positive number, false otherwise.ExampleThe code for this will be −const arr = [4, 7, 10, 13, 16, 19, 22]; const growingMarginally = arr => {    if(arr.length

const sort = ["this", "is", "my", "custom", "order"]; const myObjects = [    {"id":1, "content":"is"},    {"id":2, "content":"my"},    {"id":3, "content":"this"},    {"id":4, "content":"custom"},    {"id":5, "content":"order"} ];We are required to write a JavaScript function that takes in two such arrays and sorts the second array of objects on the basis of the first array so that the content property of objects are matched with the strings of the first array.Therefore, for the above arrays the output should look like −const output = [    {"id":3, "content":"this"},    {"id":1, "content":"is"},    {"id":2, "content":"my"},    {"id":4, "content":"custom"},    {"id":5, "content":"order"} ];ExampleThe ... Read More

We are required to write a JavaScript function that takes in an array of Numbers. The array may contain more than one greatest element (i.e., repeating greatest element).We are required to write a JavaScript function that takes in one such array and returns all the indices of the greatest element.ExampleThe code for this will be −const arr = [10, 5, 4, 10, 5, 10, 6]; const findGreatestIndices = arr => {    const val = Math.max(...arr);    const greatest = arr.reduce((indexes, element, index) => {       if(element === val){          return indexes.concat([index]);       } else {          return indexes;       };    }, []);    return greatest; } console.log(findGreatestIndices(arr));OutputAnd the output in the console will be −[ 0, 3, 5 ]

We are required to write a JavaScript function that takes in an array of two numbers as the first argument, this array specifies a number range within which we can generate random numbers.The second argument will be a single number that specifies the count of random numbers we have to generate.Then at last our function should return the greatest all random numbers generated.ExampleThe code for this will be −const range = [15, 26]; const count = 10; const randomBetweenRange = ([min, max]) => {    const random = Math.random() * (max - min) + min;    return random; }; const ... Read More

We are required to write a JavaScript function that takes in a number, say num.Then our function should return the sum of all the natural numbers between 1 and num, including 1 and num.For example, if num is −const num = 5;Then the output should be −const output = 15;because, 1+2+3+4+5 = 15We will use the below formula to solve this problem −Sum of all natural number upto n =((n*(n+1))/2)ExampleThe code for this will be −const num = 5; const sumUpto = num => {    const res = (num * (num + 1)) / 2;    return res; }; ... Read More

We are required to write a JavaScript function that takes in an array of literals.Then the function should shuffle the order of elements in any random order inplace.ExampleThe code for this will be −const letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g']; const unorderArray = arr => {    let i, pos, temp;    for (i = 0; i < 100; i++) {       pos = Math.random() * arr.length | 0;       temp = arr[pos];       arr.splice(pos, 1);       arr.push(temp);    }; } unorderArray(letters); console.log(letters);OutputAnd the output in the console will ... Read More

Suppose we have a complex JSON Object like this −const obj = {    "id": "0001",    "fieldName": "sample1",    "fieldValue" "0001",    "subList": [       {          "id": 1001,          "fieldName": "Sample Child 1",          "fieldValue": "1001",          "subList": []       },       {          "id": 1002,          "fieldName": "Sample Child 2",          "fieldValue": "1002",          "subList": []       }    ] }We are required to write ... Read More

We are required to write a JavaScript function that takes in an alphabet string and a number, say n. We should then return a new string in which all the characters are replaced by respective alphabets at position n alphabets next to them.For example, if the string and the number are −const str = 'abcd'; const n = 2;Then the output should be −const output = 'cdef';ExampleThe code for this will be −const str = 'abcd'; const n = 2; const replaceNth = (str, n) => {    const alphabet = 'abcdefghijklmnopqrstuvwxyz';    let i, pos, res = '';   ... Read More

Suppose we have a JSON Object that contains a nested array like this −const arr = {    "DATA": [       {          "BookingID": "9513",          "DutyStart": "2016-02-11 12:00:00"       },       {          "BookingID": "91157307",          "DutyStart": "2016-02-11 13:00:00"       },       {          "BookingID": "95117317",          "DutyStart": "2016-02-11 13:30:00"       },       {          "BookingID": "957266",          "DutyStart": "2016-02-12 19:15:00" ... Read More