We have an array that contains some string values as well as some false values.We are required to write a JavaScript function that takes in this array and returns a string constructed by joining values of the array and omitting false values.ExampleThe code for this will be −const arr = ["Here", "is", null, "an", undefined, "example", 0, "", "of", "a", null, "sentence"]; const joinArray = arr => {    const sentence = arr.reduce((acc, val) => {       return acc + (val || "");    }, "");    return sentence; }; console.log(joinArray(arr));OutputThe output in the console −Hereisanexampleofasentence

We are required to write a JavaScript function that takes in a negative integer and returns the sum of its digits.For example: If the number is −-5456OutputThen the output should be −5+4+5+6 10ExampleThe code for this will be −const num = -5456; const sumNum = num => {    return String(num).split("").reduce((acc, val, ind) => {       if(ind === 0){          return acc;       }       if(ind === 1){          acc -= +val;          return acc;       };       acc += +val;       return acc;    }, 0); }; console.log(sumNum(num));OutputThe output in the console −10

We are required to write a JavaScript function that takes in an array of numbers with duplicate entries and sums all the duplicate entries to one index.ExampleThe code for this will be −const input = [1, 3, 1, 3, 5, 7, 5, 3, 4]; const sumDuplicate = arr => {    const map = arr.reduce((acc, val) => {       if(acc.has(val)){          acc.set(val, acc.get(val) + 1);       }else{          acc.set(val, 1);       };       return acc;    }, new Map());    return Array.from(map, el => el[0] * el[1]); }; console.log(sumDuplicate(input));OutputThe output in the console −[ 2, 9, 10, 7, 4 ]

We are required to write a JavaScript function that takes in a number and returns the difference of the sums of the digits at even place and the digits odd place.ExampleThe code for this will be −const num = 123456; const alternateDifference = (num, res = 0, ind = 0) => {    if(num){       if(ind % 2 === 0){          res += num % 10;       }else{          res -= num % 10;       };       return alternateDifference(Math.floor(num / 10), res, ++ind);    };    return Math.abs(res); }; console.log(alternateDifference(num));OutputThe output in the console −3

We have an array of numbers like this −const arr = [-1,-2,-1,0,-1,-2,-1,-2,-1,0,1,0];We are required to write a JavaScript function that counts the consecutive groups of negative numbers in the array.ExampleThe code for this will be −const arr = [-1,-2,-1,0,-1,-2,-1,-2,-1,0,1,0]; const countClusters = arr => {    return arr.reduce((acc, val, ind) => {       if(val < 0 && arr[ind+1] >= 0){          acc++;       };       return acc;    }, 0); }; console.log(countClusters(arr));OutputThe output in the console −2

We are required to write a JavaScript function that computes the Factorial of a number n by making use of recursive approach.ExampleThe code for this will be −const num = 9; const recursiceFactorial = (num, res = 1) => {    if(num){       return recursiceFactorial(num-1, res * num);    };    return res; }; console.log(recursiceFactorial(num)); console.log(recursiceFactorial(6)); console.log(recursiceFactorial(10)); console.log(recursiceFactorial(5)); console.log(recursiceFactorial(13));OutputThe output in the console −362880 720 3628800 120 6227020800

Two numbers are said to be co-primes if there exists no common prime factor amongst them (1 is not a prime number).We are required to write a function that takes in two numbers and returns true if they are coprimes otherwise returns false.ExampleThe code for this will be −const areCoprimes = (num1, num2) => {    const smaller = num1 > num2 ? num1 : num2;    for(let ind = 2; ind < smaller; ind++){       const condition1 = num1 % ind === 0;       const condition2 = num2 % ind === 0;       ... Read More

We are required to write a JavaScript function that finds how many times a specific letter is appearing in the sentence.ExampleThe code for this will be −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 ... Read More

We are required to write a JavaScript function that takes in an array of Numbers and returns a new array with elements as the sum of two consecutive elements from the original array.For example, if the input array is −const arr1 = [1, 1, 2, 7, 4, 5, 6, 7, 8, 9];Then the output should be −const output = [2, 9, 9, 13, 17]ExampleThe code for this will be −const arr11 = [1, 1, 2, 7, 4, 5, 6, 7, 8, 9]; const consecutiveSum = arr => {    const res = [];    for(let i = 0; i < arr.length; i += 2){       res.push(arr[i] + (arr[i+1] || 0));    };    return res; }; console.log(conseutiveSum(arr1));OutputThe output in the console −[ 2, 9, 9, 13, 17 ]

We are required to write a JavaScript function that takes in two arrays of Numbers and checks whether all the elements of the first array exist in the second or not.ExampleThe code for this will be −const arr1 = [34, 78, 89]; const arr2 = [78, 67, 34, 99, 56, 89]; const multipleIncludes = (first, second) => {    const indexArray = first.map(el => {       return second.indexOf(el);    });    return indexArray.indexOf(-1) === -1; } console.log(multipleIncludes(arr1, arr2));OutputThe output in the console −true