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Front End Technology Articles
Page 457 of 652
Alternate addition multiplication in an array - JavaScript
We are required to write a JavaScript function that takes in an array of numbers and returns the alternative multiplicative sum of the elementsFor example −If the array is −const arr = [1, 2, 4, 1, 2, 3, 4, 3];then the output should be calculated like this −1*2+4*1+2*3+4*3 2+4+6+12And the output should be −24ExampleLet's write the code for this −const arr = [1, 2, 4, 1, 2, 3, 4, 3]; const alternateOperation = arr => { const productArr = arr.reduce((acc, val, ind) => { if(ind % 2 === 1){ return acc; }; acc.push(val * (arr[ind + 1] || 1)); return acc; }, []); return productArr.reduce((acc, val) => acc + val); }; console.log(alternateOperation(arr));OutputThe output in the console: −24
Read MoreConvert object to a Map - JavaScript
Suppose we have an object like this −const obj = { name: "Vikas", age: 45, occupation: "Frontend Developer", address: "Tilak Nagar, New Delhi", experience: 23, };We are required to write a JavaScript function that takes in such an object with key value pairs and converts it into a Map.ExampleLet's write the code for this −const obj = { name: "Vikas", age: 45, occupation: "Frontend Developer", address: "Tilak Nagar, New Delhi", experience: 23, salary: "98000" }; const objectToMap = obj => { const keys = Object.keys(obj); const map ...
Read MoreConvert nested array to string - JavaScript
We are required to write a JavaScript function that takes in a nested array of literals and converts it to a string by concatenating all the values present in it to the stringconst arr = [ 'hello', [ 'world', 'how', [ 'are', 'you', [ 'without', 'me' ] ] ] ];ExampleLet’s say the following is our nested array −const arr = [ 'hello', [ 'world', 'how', [ 'are', 'you', [ 'without', 'me' ] ] ] ]; const arrayToString = (arr) => { let str = ''; for(let i = 0; i < arr.length; i++){ if(Array.isArray(arr[i])){ str += arrayToString(arr[i]); }else{ str += arr[i]; }; }; return str; }; console.log(arrayToString(arr));OutputFollowing is the output in the console −helloworldhowareyouwithoutme
Read MoreComparing ascii scores of strings - JavaScript
ASCII CodeASCII is a 7-bit character code where every single bit represents a unique character.Every English alphabet has a unique decimal ascii code.We are required to write a function that takes in two strings and calculates their ascii scores (i.e., the sum of ascii decimal of each character of string) and returns the difference.ExampleLet's write the code for this −const str1 = 'This is the first string.'; const str2 = 'This here is the second string.'; const calculateScore = (str = '') => { return str.split("").reduce((acc, val) => { return acc + val.charCodeAt(0); }, 0); ...
Read MoreComparing forEach() and reduce() for summing an array of numbers in JavaScript.
We are required to compare the time taken respectively by the ES6 functions forEach() and reduce() for summing a huge array of numbers.As we can't have a huge array of numbers here, we will simulate the magnitude of array by performing the summing operation for large number of times (iterations)ExampleLet's write the code for this −const arr = [1, 4, 4, 54, 56, 54, 2, 23, 6, 54, 65, 65]; const reduceSum = arr => arr.reduce((acc, val) => acc + val); const forEachSum = arr => { let sum = 0; arr.forEach(el => sum += el); return ...
Read MorePrime numbers in a range - JavaScript
We are required to write a JavaScript function that takes in two numbers, say, a and b and returns the total number of prime numbers between a and b (including a and b, if they are prime).For example −If a = 2, and b = 21, the prime numbers between them are 2, 3, 5, 7, 11, 13, 17, 19And their count is 8. Our function should return 8.Let’s write the code for this function −ExampleFollowing is the code −const isPrime = num => { let count = 2; while(count < (num / 2)+1){ if(num ...
Read MoreFinding least number of notes to sum an amount - JavaScript
Suppose, we have a currency system where we have denominations of 1000 units, 500 units, 100 units, 50 units, 20 units, 10 units, 5 units, 2 units and 1 unit.Given a specific amount, we are required to write a function that calculates the least number of total denominations that sum up to the amount.For example, if the amount is 512, The least number of notes that will add up to it will be: 1 unit of 500, 1 unit of 10 and 1 unit of 2.So, in this we for 512, our function should return 3, i.e., the total count ...
Read MoreProgram to append two given strings such that, if the concatenation creates a double character then omit one of the characters - JavaScript
We are required to write a JavaScript function that takes in two strings and concatenates the second string to the first string.If the last character of the first string and the first character of the second string are the same then we have to omit one of those characters. Let’s say the following are our strings in JavaScript −const str1 = 'Food'; const str2 = 'dog';Let’s write the code for this function −const str1 = 'Food'; const str2 = 'dog'; const concatenateStrings = (str1, str2) => { const { length: l1 } = str1; const { length: l2 ...
Read MoreGetting tomorrow and day after tomorrow date in JavaScript
Using the Date class of JavaScript whose object new Date() returns a JavaScript date for the current day, we have to find the date of the next two days.This is a fairly simple problem and we can achieve this with a few lines of code. At first, get today’s date −// getting today's date const today = new Date();Let’s write the code for this function −// getting today's date const today = new Date(); // initializing tomorrow with today's date const tomorrow = new Date(today); // increasing a day in tomorrow and setting it to tomorrow tomorrow.setDate(tomorrow.getDate() + 1); const ...
Read MoreReduce an array to the sum of every nth element - JavaScript
We are required to write a JavaScript function that takes in an array of numbers and returns the cumulative sum of every number present at the index that is a multiple of n from the array.Let’s write the code for this function −const arr = [1, 4, 5, 3, 5, 6, 12, 5, 65, 3, 2, 65, 9]; const num = 2; const nthSum = (arr, num) => { let sum = 0; for(let i = 0; i < arr.length; i++){ if(i % num !== 0){ continue; }; sum += arr[i]; }; return sum; }; console.log(nthSum(arr, num));OutputFollowing is the output in the console −99Above, we added every 2nd element beginning with index 0 i.e.1+5+5+12+65+2+9 = 99
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