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Web Development Articles
Page 164 of 801
Sum of distinct elements of an array in JavaScript
Suppose, we have an array of numbers like this − const arr = [1, 5, 2, 1, 2, 3, 4, 5, 7, 8, 7, 1]; We are required to write a JavaScript function that takes in one such array and counts the sum of all distinct elements of the array. For example: The output for the array mentioned above will be − 30 Method 1: Using lastIndexOf() and indexOf() This approach checks if the current index is the last occurrence of each element, ensuring we count each distinct element ...
Read MoreReturn the index of first character that appears twice in a string in JavaScript
We are required to write a JavaScript function that takes in a string and returns the index of the first character that appears twice in the string. If there is no such character then we should return -1. Syntax function firstRepeating(str) { // Implementation here } Example The code for this will be − const str = 'Hello world, how are you'; const firstRepeating = str => { const map = new Map(); for(let i = 0; i < ...
Read MoreFind array elements that are out of order in JavaScript
Suppose we have an array of sorted numbers but some elements of the array are out of their sorted order. We are required to write a JavaScript function that takes in one such array and returns a subarray of all those elements that are out of order. Example The code for this will be − const arr = ["2", "3", "7", "4", "5", "6", "1"]; const findOutOfOrder = arr => { let notInOrder = []; notInOrder = arr.filter((el, ind) => { ...
Read MoreGrouping names based on first letter in JavaScript
Suppose, we have an array of names like this: const arr = ["Simon", "Mike", "Jake", "Lara", "Susi", "Blake", "James"]; We are required to write a JavaScript function that takes in one such array. The function should return an array of objects with two properties: letter -> the letter on which the names are grouped names -> an array of names that falls in that group Example The code for this will be: const arr = ["Simon", "Mike", "Jake", "Lara", "Susi", "Blake", ...
Read MoreHow to iterate over objects in array and sum a property in JavaScript
Suppose we have an array of objects like this: const arr = [ { duration: 10, any: 'fields' }, { duration: 20, any: 'other fields' }, { duration: 15, any: 'some other fields' } ...
Read MoreGet values that are not present in another array in JavaScript
We are given two arrays: (arr1 and arr2) − arr1 contains some literal values. arr2 contains objects that map some literal values. We are required to write a JavaScript function that takes in two such arrays. Then the function should return an array of all the elements from arr1 that are not mapped by objects in arr2. Example The code for this will be − const arr1 = [111, 222, 333, 444]; const arr2 = [ { identifier: 111 }, ...
Read MoreFinding shortest word in a string in JavaScript
We are required to write a JavaScript function that takes in a string and returns the shortest word from the string. For example: If the input string is: const str = 'This is a sample string'; Then the output should be: 'a' Using Array.reduce() Method This approach splits the string into words and uses reduce() to find the shortest word by comparing lengths: const str = 'This is a sample string'; const findSmallest = str => { const strArr = str.split(' '); ...
Read MoreMap numbers to characters in JavaScript
When mapping numbers to characters in JavaScript, we need to convert digits to their corresponding alphabetical positions (1='a', 2='b', etc.). A number can be mapped in multiple ways by grouping digits differently. For example, the number 12145 can be interpreted as: 1, 2, 1, 4, 5 → a, b, a, d, e 12, 1, 4, 5 → l, a, d, e 12, 14, 5 → l, n, e However, combinations like 1, 2, 1, 45 are invalid because 45 exceeds the alphabet range (1-26). Solution Approach We use recursion to explore all valid digit ...
Read MoreRetaining array elements greater than cumulative sum using reduce() in JavaScript
We need to write a JavaScript function that takes an array of numbers and returns a new array containing only elements that are greater than the cumulative sum of all previous elements. We'll solve this using the Array.prototype.reduce() method. Problem Understanding For each element in the array, we compare it with the sum of all elements that came before it. If the current element is greater than this cumulative sum, we include it in the result array. Example Let's implement the solution using reduce(): const arr = [1, 2, 30, 4, 5, 6]; ...
Read MoreRemoving duplicate values in a twodimensional array in JavaScript
When working with two-dimensional arrays in JavaScript, you may need to remove duplicate values that appear across different sub-arrays. This article shows how to create a function that removes all duplicate values from a 2D array, keeping only the first occurrence of each value. Problem Statement We need to write a JavaScript function that takes a two-dimensional array and returns a new array where duplicate values across all sub-arrays are removed, preserving only the first occurrence of each value. Example Here's how to implement this functionality: const arr = [ ...
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