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Javascript Articles
Page 394 of 534
Find duplicate element in a progression of first n terms JavaScript
Let’s say, we are given an array of numbers that contains first n natural numbers, but one element appears twice in the array, so the total number of elements is n+1. Our job is to write a function that takes in the array and returns the number that appears twice in linear time.Method 1: Using Array.prototype.reduce()This is a bit trickier approach but the most compressed in terms of code written. First, let’s see the code for it −const arr = [1, 4, 8, 5, 6, 7, 9, 2, 3, 7]; const duplicate = a => a.reduce((acc, val, ind) => val+acc- ...
Read MoreHighest and lowest in an array JavaScript
We are required to write a function that takes in an array of numbers and returns the difference between its highest and lowest number.At first, create an array −const arr = [23, 54, 65, 76, 87, 87, 431, -6, 22, 4, -454];Now, find maximum and minimum values with Math.max() and Math.min() methods, respectively −const arrayDifference = (arr) => { let min, max; arr.forEach((num, index) => { if(index === 0){ min = num; max = num; }else{ min = Math.min(num, min); ...
Read MoreMerge two arrays with alternating Values in JavaScript
Let’s say, we are required to write a function that takes in two arrays and returns a new array that contains values in alternating order from first and second array. Here, we will just loop over both the arrays simultaneously picking values from them one after the other and feed them into the new array.The full code for doing the same will be −Exampleconst arr1 = [34, 21, 2, 56, 17]; const arr2 = [12, 86, 1, 54, 28]; let run = 0, first = 0, second = 0; const newArr = []; while(run < arr1.length + arr2.length){ if(first ...
Read MoreCompletely removing duplicate items from an array in JavaScript
We are required to write a function that takes in an array and returns a new array that have all duplicate values removed from it.The values that appeared more than once in the original array should not even appear for once in the new array.For example, if the input is −const arr = [23, 545, 43, 232, 32, 43, 23, 43];The output should be −const output = [545, 232, 32];Understanding the difference −Array.prototype.indexOf() → It returns the index of first occurrence of searched string if it exists, otherwise -1.Array.prototype.lastIndexOf() → It returns the index of last occurrence of searched string ...
Read MoreConvert number to alphabet letter JavaScript
We are required to write a function that takes in a number between 1 and 26 (both inclusive) and returns the corresponding English alphabet for it. (capital case) If the number is out of this range return -1.For example −toAlpha(3) = C toAlpha(18) = RAnd so on.The ASCII CodesASCII codes are the standard numerical representation of all the characters and numbers present on our keyboard and many for.The capital English alphabets are also mapped in the ascii char codes, they start from 65 and goes all the way up to 90, with 65 being the value for ‘A’, 66 for ...
Read MoreGet the property of the difference between two objects in JavaScript
Let’s say, we are given two objects that have similar key value pairs with one or key having different values in both objects. Our job is to write a function that takes in the two objects as argument and returns the very first key it finds having different values. If all the keys have exact same values, it should return -1.Here are the sample objects −const obj1 = { name: 'Rahul Sharma', id: '12342fe4554ggf', isEmployed: true, age: 45, salary: 190000, job: 'Full Stack Developer', employedSince: 2005 } const obj2 = { name: ...
Read MoreHow to make a list of partial sums using forEach JavaScript
We have an array of numbers like this −const arr = [1, 1, 5, 2, -4, 6, 10];We are required to write a function that returns a new array, of the same size but with each element being the sum of all elements until that point.So, the output should look like −const output = [1, 2, 7, 9, 5, 11, 21];Let’s write the function partialSum(). The full code for this function will be −Exampleconst arr = [1, 1, 5, 2, -4, 6, 10]; const partialSum = (arr) => { const output = []; arr.forEach((num, index) => { ...
Read MoreRecursive sum all the digits of a number JavaScript
Let’s say, we are required to create a function that takes in a number and finds the sum of its digits recursively until the sum is a one-digit number.For example −findSum(12345) = 1+2+3+4+5 = 15 = 1+5 = 6So, the output should be 6.Let’s write the code for this function findSum() −Example// using recursion const findSum = (num) => { if(num < 10){ return num; } const lastDigit = num % 10; const remainingNum = Math.floor(num / 10); return findSum(lastDigit + findSum(remainingNum)); } console.log(findSum(2568));We check if the number is less than 10, ...
Read MoreHow to sum elements at the same index in array of arrays into a single array? JavaScript
We have an array of arrays and are required to write a function that takes in this array and returns a new array that represents the sum of corresponding elements of original array.If the original array is −[ [43, 2, 21], [1, 2, 4, 54], [5, 84, 2], [11, 5, 3, 1] ]Then the output should be −[60, 93, 30, 55]Let’s write a sample function addArray()The full code for this function will be −Exampleconst arr = [ [43, 2, 21], [1, 2, 4, 54], [5, 84, 2], [11, 5, 3, 1] ]; const sumArray = (array) => { ...
Read MoreConverting Odd and Even-indexed characters in a string to uppercase/lowercase in JavaScript?
We need to write a function that reads a string and converts the odd indexed characters in the string to upperCase and the even ones to lowerCase and returns a new string.Full code for doing the same will be −Exampleconst text = 'Hello world, it is so nice to be alive.'; const changeCase = (str) => { const newStr = str .split("") .map((word, index) => { if(index % 2 === 0){ return word.toLowerCase(); }else{ return word.toUpperCase(); } }) ...
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