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Object Oriented Programming Articles
Page 193 of 588
Omitting false values while constructing string in JavaScript
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
Read MoreNegative number digit sum in JavaScript
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
Read MoreSum all duplicate values in array in JavaScript
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 ]
Read MoreDifference of digits at alternate indices in JavaScript
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
Read MoreFinding clusters of consecutive negative integers in JavaScript
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
Read MoreConsecutive elements sum array in JavaScript
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 ]
Read MoreJavaScript Array: Checking for multiple values
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
Read MorePadding a string with random lowercase alphabets to fill length in JavaScript
We are required to write a function that takes in two arguments, first is a string and second is a number. The length of string is always less than or equal to the number. We have to insert some random lowercase alphabets at the end of the string so that its length becomes exactly equal to the number and we have to return the new string.ExampleLet’s write the code for this function −const padString = (str, len) => { if(str.length < len){ const random = Math.floor(Math.random() * 26); const randomAlpha = String.fromCharCode(97 + ...
Read MorePushing positives and negatives to separate arrays in JavaScript
We are required to write a function that takes in an array and returns an object with two arrays positive and negative. They both should be containing all positive and negative items respectively from the array.We will be using the Array.prototype.reduce() method to pick desired elements and put them into an object of two arrays.ExampleThe code for this will be −const arr = [97, -108, 13, -12, 133, -887, 32, -15, 33, -77]; const splitArray = (arr) => { return arr.reduce((acc, val) => { if(val < 0){ acc['negative'].push(val); }else{ ...
Read MoreGrouping array values in JavaScript
Suppose we have an array of objects containing some years and weeks data like this −const arr = [ {year: 2017, week: 45}, {year: 2017, week: 46}, {year: 2017, week: 47}, {year: 2017, week: 48}, {year: 2017, week: 50}, {year: 2017, week: 52}, {year: 2018, week: 1}, {year: 2018, week: 2}, {year: 2018, week: 5} ];We are required to write a JavaScript function that takes in one such array. The function should return a new array where all the objects that have common value for the "year" property are grouped into ...
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