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

The correct syntax to set the innerHTML is as follows −document.getElementById(“yourIdName”).innerHTML=”yourValue”;Let’s now see how to set the innerHTML −Example Live Demo Document Username:    document.getElementById('test').innerHTML = 'Enter Some value into the text box'; 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 −

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 −

Let’s say the following is our array with non-null, null and undefined values −var firstName=["John",null,"Mike","David","Bob",undefined];You can check for undefined or null cases by using the following code −Examplevar firstName=["John",null,"Mike","David","Bob",undefined]; for(var index=0;index node demo203.js John Mike David Bob

Let’s say the following is our array;var theValuesIn3DArray = [75, [18, 89], [56, [97], [99]]];Use the concept of flat() within the Math.max() to get the largest number.Examplevar theValuesIn3DArray = [75, [18, 89], [56, [97], [99]]]; Array.prototype.findTheLargestNumberIn3dArray = function (){    return Math.max(...this.flat(Infinity)); } console.log("The largest number in 3D array is="); console.log(theValuesIn3DArray.findTheLargestNumberIn3dArray());To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo202.js.OutputThis will produce the following output −PS C:\Users\Amit\javascript-code> node demo202.js The largest number in 3D array is= 99