We are required to write a function that takes in a ‘HH:MM:SS’ string and returns the number of seconds. For example −countSeconds(‘12:00:00’) //43200 countSeconds(‘00:30:10’) //1810Let’s write the code for this. We will split the string, convert the array of strings into an array of numbers and return the appropriate number of seconds.The full code for this will be −Exampleconst timeString = '23:54:43'; const other = '12:30:00'; const withoutSeconds = '10:30'; const countSeconds = (str) => {    const [hh = '0', mm = '0', ss = '0'] = (str || '0:0:0').split(':');    const hour = parseInt(hh, 10) || 0;   ... Read More

We are given a string that contains some repeating words separated by dash (-) like this −const str = 'monday-sunday-tuesday-tuesday-sunday-sunday-monday-mondaymonday';Now our job is to write a function that returns an array of objects, where each object contains two properties value and count, value is the word in the string (Monday, Tuesday, Sunday) and count is their consecutive appearance count.Like for the above string, this array would look something like this −const arr = [{    val: 'monday',    count: 1 }, {    val: 'sunday',    count: 1 }, {    val: 'tuesday',    count: 2 }, {    val: ... Read More

We are given a string and an array of strings; our job is to write a function that removes all the substrings that are present in the array from the string.These substrings are complete words so we are also supposed to remove leading or trailing whitespace so that no two whitespaces appear together.Therefore, let’s write the code for this function −Exampleconst string = "The weather in Delhi today is very similar to the weather in Mumbai"; const words = [    'shimla', 'rain', 'weather', 'Mumbai', 'Pune', 'Delhi', 'tomorrow', 'today', 'yesterday' ]; const removeWords = (str, arr) => {    return ... Read More

We are required to write a function getAverage() that accepts an array of arrays of numbers and we are required to return a new array of numbers that contains the average of corresponding subarrays.Let’s write the code for this. We will map over the original array, reducing the subarray to their averages like this −Exampleconst arr = [[1,54,65,432,7,43,43, 54], [2,3], [4,5,6,7]]; const secondArr = [[545,65,5,7], [0,0,0,0], []]; const getAverage = (arr) => {    const averageArray = arr.map(sub => {       const { length } = sub;       return sub.reduce((acc, val) => acc + (val/length), 0);    });    return averageArray; } console.log(getAverage(arr)); console.log(getAverage(secondArr));OutputThe output in the console will be −[ 87.375, 2.5, 5.5 ] [ 155.5, 0, 0 ]

We are required to write a function that takes in an array arr and a number n between 0 and 100 (both inclusive) and returns the n% part of the array. Like if the second argument is 0, we should expect an empty array, complete array if it’s 100, half if 50, like that.And if the second argument is not provided it should default to 50. Therefore, the code for this will be −Exampleconst numbers = [3, 6, 8, 6, 8, 4, 26, 8, 7, 4, 23, 65, 87, 98, 54, 32, 57, 87]; const byPercent = (arr, n = ... Read More

We are required to write a function that takes in two strings, we have to return a new string which is just the same as the first of the two arguments but have second argument prepended to its every word.For example −Input → ‘hello stranger, how are you’, ‘@@’ Output → ‘@@hello @@stranger, @@how @@are @@you’If second argument is not provided, take ‘#’ as default.Exampleconst str = 'hello stranger, how are you'; const prependString = (str, text = '#') => {    return str    .split(" ")    .map(word => `${text}${word}`)       .join(" "); }; console.log(prependString(str)); console.log(prependString(str, '43'));OutputThe ... Read More

We are required to write a function that removes duplicate objects from an array and returns a new one. Consider one object the duplicate of other if they both have same number of keys, same keys and same value for each key.Let’s write the code for this −We will use a map to store distinct objects in stringified form and once we see a duplicate key we omit it otherwise we push the object into the new array −Exampleconst arr = [    {       "timestamp": 564328370007,       "message": "It will rain today"    },   ... Read More

We are required to write a function that takes in a string, trims it off any whitespaces, converts it to lowercase and returns an array of numbers describing corresponding characters positions in the english alphabets, any whitespace or special character within the string should be ignored.For example −Input → ‘Hello world!’ Output → [8, 5, 12, 12, 15, 23, 15, 18, 12, 4]The code for this will be −Exampleconst str = 'Hello world!'; const mapString = (str) => {    const mappedArray = [];    str    .trim()    .toLowerCase()    .split("")    .forEach(char => {       const ascii = char.charCodeAt();       if(ascii >= 97 && ascii

Let’s say, we are required to write a function that takes an array as input and returns the maximum slice of the array which contains no more than two different numbers. If we closely examine this problem this involves checking for a stable sub array and iterating over the original array.Therefore, the sliding window algorithm is very suitable for this. The code for solving this problem via sliding window algorithm will be −Exampleconst arr = [1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 6, 2, 1, 8, 1, 1 ,1 ,1, 8, 1, 1, 8, 8]; const map ... Read More

Tracking differences between elements in an array is a fundamental task in data analysis and software development. Whether you're analyzing trends in numerical data, measuring changes over time, or debugging an application's behavior, calculating these differences can provide valuable insights. In JavaScript, this task is often approached using various techniques, including loops and modern functional programming methods like the map() function. Here are two methods to calculate differences between elements in an array: Iterative Loop and Functional Programming using the map. Problem Statement We are given an array of Number literals, and we are required to write a function that returns ... Read More