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Front End Technology Articles
Page 232 of 652
Sort by index of an array in JavaScript
Sorting an array of objects by a specific property is a common task in JavaScript. This tutorial demonstrates how to sort objects by their index property and extract specific values. Problem Statement Suppose we have the following array of objects: const arr = [ { 'name': 'd', 'index': 3 }, { 'name': 'c', ...
Read MoreTurning a 2D array into a sparse array of arrays in JavaScript
Suppose, we have a 2-D array like this − const arr = [ [3, 1], [2, 12], [3, 3] ]; We are required to write a JavaScript function that takes in one such array. The function should then create a new 2-D array that contains all elements initialized to undefined other than the element's index present in the input array. Therefore, for the input array: output[3][1] = 1; output[2][12] = 1; output[3][3] = 1; And rest all elements ...
Read MoreAlphanumeric sorting using JavaScript
We have a mixed array that we need to sort by alphabet and then by digit. This requires a custom sorting function that handles both alphabetical and numerical parts correctly. const arr = ['Ab-1', 'Ab-11', 'Ab-12', 'ab-10', 'ab-100', 'ab-101', 'ab2', 'ab-3', 'ab-105']; console.log("Original array:", arr); Original array: [ 'Ab-1', 'Ab-11', 'Ab-12', 'ab-10', 'ab-100', 'ab-101', 'ab2', 'ab-3', 'ab-105' ] The Problem with Standard Sort JavaScript's default string sort doesn't handle numbers correctly. It treats "10" as smaller than "2" because it compares character ...
Read MoreEnter a number and write a function that adds the digits together on button click in JavaScript
We are required to write a JavaScript program that provides users an input to fill in a number. And upon filling when the user clicks the button, we should display the sum of all the digits of the number. HTML Structure First, let's create the HTML elements needed for our application: Submit JavaScript Implementation Here's the JavaScript function that calculates the sum of digits: function myFunc() { var num = document.getElementById('digits').value; var tot = 0; ...
Read MoreJavaScript - summing numbers from strings nested in array
When working with arrays containing string numbers (like credit card numbers), you often need to extract and sum the numeric values. This article shows how to find the string with the greatest sum of digits. Problem Statement Given an array of credit card numbers as strings, we need to find the card with the highest sum of digits. If multiple cards have the same sum, return the last one encountered. const arr = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260']; Solution Approach The solution involves two main steps: extracting numbers from each string and calculating their ...
Read MoreLongest decreasing subsequence subarray in JavaScript
We are required to write a JavaScript function that takes in an array of integers and returns the length of the longest consecutive decreasing subsequence (subarray) from the array. Problem Statement Given an array of integers, find the length of the longest contiguous subsequence where each element is smaller than the previous one. For example, if the input array is: const arr = [5, 2, 5, 4, 3, 2, 4, 6, 7]; The longest decreasing subsequence is [5, 4, 3, 2] with length 4. Solution Approach We'll track the current decreasing ...
Read MoreFuzzy Search Algorithm in JavaScript
Fuzzy search allows finding strings that match a pattern even when characters are not consecutive. In JavaScript, we can implement a fuzzy search algorithm that checks if characters from a search query appear in the same order within a target string. How Fuzzy Search Works The algorithm loops through each character of the search query and verifies that all characters exist in the target string in the same sequential order, though they don't need to be adjacent. For example: ('a haystack with a needle').fuzzySearch('hay sucks'); // false ('a haystack with a needle').fuzzySearch('sack hand'); // true ...
Read MoreModify an array based on another array JavaScript
When working with arrays in JavaScript, you might need to modify one array based on patterns or elements found in another array. This article demonstrates how to join consecutive elements from a reference array when they appear as combined phrases in a second array. Problem Statement Suppose we have a reference array of individual words: const reference = ["your", "majesty", "they", "are", "ready"]; And we want to modify it based on another array that contains some words joined together: const another = ["your", "they are"]; The goal is to create ...
Read MoreCalculating the sum of digits of factorial JavaScript
We are required to write a JavaScript function that takes in a number. The function should first calculate the factorial of that number and then it should return the sum of the digits of the calculated factorial. For example, for the number 6, the factorial will be 720, so the sum of digits (7 + 2 + 0) should be 9. Understanding the Problem This problem involves two steps: Calculate the factorial of a given number Sum all digits in the factorial result Step 1: Calculate ...
Read MoreInsert a number into a sorted array of numbers JavaScript
We are required to write a JavaScript function that takes in a sorted array of numbers as the first argument and a single number as the second argument. The function should push the number specified as the second argument into the array without distorting the sorting of the elements. We are required to do this without creating another array. Approach: Binary Search with In-Place Insertion The solution uses binary search to find the correct insertion position, then shifts elements using a swapping technique to maintain order without extra space. Example const arr = ...
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