We have two arrays of objects like these −const blocks = [    { id: 1 },    { id: 2 },    { id: 3 },    { id: 4 }, ] const containers = [    { block: { id: 1 } },    { block: { id: 2 } },    { block: { id: 3 } }, ]We are required to write a function that checks each object of blocks array with the block key of each object of containers array and see if there exists any id in blocks array that is not present in ... Read More

We have an array of numbers like this −const arr = [-1, -2, -1, 0, -1, -2, -1, -2, -1, 0, 1, 0];Let’s say, we are required to write a JavaScript function that counts the consecutive groups of negative numbers in the array.Like here we have consecutive negatives from index 0 to 2 which forms one group and then from 4 to 8 forms the second groupSo, for this array, the function should return 2.ExampleLet’s write the code −const arr = [-1, -2, -1, 0, -1, -2, -1, -2, -1, 0, 1, 0]; const countNegativeGroup = arr => {   ... Read More

We are required to write a JavaScript function that computes the Factorial of a number n by making use of recursive approach.Here, we are finding the factorial recursion and creating a custom function recursiceFactorial() −const num = 9; const recursiceFactorial = (num, res = 1) => {    if(num){       return recursiceFactorial(num-1, res * num);    };    return res; };Now, we will call the function and pass the value to find recursion −console.log(recursiceFactorial(num)); console.log(recursiceFactorial(6)); console.log(recursiceFactorial(10));ExampleLet’s write the code for this function −const num = 9; const recursiceFactorial = (num, res = 1) => {    if(num){   ... Read More

Let’s say, we have an array of objects like this −data = [    {"Age":26, "Level":8},    {"Age":37, "Level":9},    {"Age":32, "Level":5},    {"Age":31, "Level":11},    {"Age":null, "Level":15},    {"Age":null, "Level":17},    {"Age":null, "Level":45} ];We are required to write a JavaScript function that calculates the average level for all the objects that have a truthy value for age propertyLet’s write the code for this function −ExampleFollowing is the code −data = [    {"Age":26, "Level":8},    {"Age":37, "Level":9},    {"Age":32, "Level":5},    {"Age":31, "Level":11},    {"Age":null, "Level":15},    {"Age":null, "Level":17},    {"Age":null, "Level":45} ]; const findAverage = arr => { ... Read More

Two numbers are said to be co-primes if there exists no common prime factor amongst them (1 is not a prime number)For example −4 and 5 are co-primes 9 and 14 are co-primes 18 and 35 are co-primes 21 and 57 are not co-prime because they have 3 as the common prime factorWe are required to write a function that takes in two numbers and returns true if they are co-primes otherwise returns falseExampleLet’s write the code for this function −const areCoprimes = (num1, num2) => {    const smaller = num1 > num2 ? num1 : num2;    for(let ... Read More

We are required to write a JavaScript function that finds how many times a specific letter is appearing in the sentenceExampleLet’s write the code for this function −const string = 'This is just an example string for the program'; const countAppearances = (str, char) => {    let count = 0;    for(let i = 0; i < str.length; i++){    if(str[i] !== char){       // using continue to move to next iteration          continue;       };       // if we reached here it means that str[i] and char are same ... Read More

We are required to write a JavaScript function that takes in three numbers A, B and N, and finds the total number of N-digit numbers whose sum of digits at even positions and odd positions are divisible by A and B respectively.ExampleLet’s write the code for this function −const indexSum = (num, sumOdd = 0, sumEven = 0, index = 0) => {    if(num){        if(index % 2 === 0){            sumEven += num % 10;        }else{            sumOdd += num % 10;       ... Read More

Let’s say, we are required to write a JavaScript function that takes in an array and a number n and rotates the array by n elementsFor example: If the input array is −const arr = [12, 6, 43, 5, 7, 2, 5];and number n is 3, Then the output should be −const output = [5, 7, 2, 5, 12, 6, 43];Let’s write the code for this function −ExampleFollowing is the code −// rotation const arr = [12, 6, 43, 5, 7, 2, 5]; const rotateByOne = arr => {    for(let i = 0; i < arr.length-1; i++){     ... Read More

Let’s say the following is our array with non-empty and empty values −studentDetails[2] = "Smith"; studentDetails[3] = ""; studentDetails[4] = "UK"; function arrayHasEmptyStrings(studentDetails) {    for (var index = 0; index < studentDetails.length; index++) {To check arrays for empty strings, the syntax is as follows. Set such condition for checking −if(yourArrayObjectName[yourCurrentIndexvalue]==””){    // insert your statement } else{    // insert your statement }Examplevar studentDetails = new Array(); studentDetails[0] = "John"; studentDetails[1] = ""; studentDetails[2] = "Smith"; studentDetails[3] = ""; studentDetails[4] = "UK"; function arrayHasEmptyStrings(studentDetails) {    for (var index = 0; index < studentDetails.length; index++) {    if (studentDetails[index] ... Read More

For this, extract the time of specific date time and call the function using setTimeout(). The code is as follows −Example Live Demo Document    function timeToAlert() {       alert("The time is 9:36 AM");    }    var timeIsBeing936 = new Date("08/09/2020 09:36:00 AM").getTime()    , currentTime = new Date().getTime()    , subtractMilliSecondsValue = timeIsBeing936 - currentTime;    setTimeout(timeToAlert, subtractMilliSecondsValue); To run the above program, save the file name “anyName.html(index.html)” and right click on the file. Select the option “Open with Live Server” in VS Code editor.OutputThis will produce the following output −