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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to wrap setTimeout() method in a promise?
The setTimeout() method executes code or functions after a specified delay in milliseconds. When working with promises, you can wrap setTimeout() to create delayed asynchronous operations that resolve or reject after a specific time period. In JavaScript, a promise is an object that represents the eventual completion of an asynchronous operation. Here, we will learn to resolve or reject promises after some delay using the setTimeout() method. Basic Promise Without setTimeout() First, let's see a basic promise that resolves immediately without any delay: Using Promises without setTimeout() method ...
Read MoreRecursive string parsing into object - JavaScript
Recursive string parsing transforms an array of dot-separated strings into a nested JavaScript object structure. This technique is useful for converting flat configuration paths into hierarchical data structures. Problem Description Given an array of strings following the pattern x.y.x.y..., we need to create a nested object where the last segment becomes a value in an array, and preceding segments form the nested structure. For example, if the input array is: const arr = [ "country.UK.level.1", "country.UK.level.2", "country.US.level.1", "country.UK.level.3" ...
Read MoreHyphen string to camelCase string in JavaScript
Converting hyphen-separated strings to camelCase is a common requirement in JavaScript development. We need to transform strings like 'this-is-an-example' into 'thisIsAnExample'. Problem Statement Given a string with words separated by hyphens: const str = 'this-is-an-example'; We need to convert it into camelCase format: const output = 'thisIsAnExample'; Using split(), map(), and join() Method The most straightforward approach splits the string by hyphens, capitalizes each word except the first, and joins them back: const str = 'this-is-an-example'; const changeToCamel = str => { ...
Read MoreHow to sort array by first item in subarray - JavaScript?
In JavaScript, you can sort an array of subarrays based on the first element of each subarray using the sort() method with a custom comparison function. The Problem Consider an array where each element is itself an array, and you want to sort by the first item in each subarray: var studentDetails = [ [89, "John"], [78, "Mary"], [94, "Alice"], [47, "Bob"], [33, "Carol"] ]; Sorting in Descending Order To sort by the ...
Read MoreReturn Vowels in a string in JavaScript
We are required to write a JavaScript function that takes in a string that might contain some alphabets. The function should count and return the number of vowels that exists in the string. Syntax function countVowels(str) { // Convert to lowercase for case-insensitive comparison // Loop through each character // Check if character is a vowel (a, e, i, o, u) // Return the count } Example: Using for Loop Following is the code − const ...
Read MoreFinding the third maximum number within an array in JavaScript
Finding the third maximum number in a JavaScript array requires handling duplicates and edge cases where fewer than three unique values exist. The task is to return the third largest unique number from an array. If fewer than three unique numbers exist, return the maximum number instead. Problem Example For the input array: [34, 67, 31, 87, 12, 30, 22] The unique numbers sorted in descending order are: [87, 67, 34, 31, 30, 22, 12] The third maximum is 34. Solution Approach The algorithm works by: ...
Read MoreSumming up to amount with fewest coins in JavaScript
The coin change problem is a classic dynamic programming challenge where we need to find the minimum number of coins required to make a specific amount. If the amount cannot be achieved with the given coin denominations, we return -1. Problem Statement We need to write a JavaScript function that takes two parameters: arr: An array containing different coin denominations amount: The target amount we want to achieve The function should return the minimum number of coins needed to sum up to the target amount. Example Input and Output const arr ...
Read MoreRemoving letters to make adjacent pairs different using JavaScript
We are required to write a JavaScript function that takes in a string containing only 'A', 'B' and 'C'. Our function should find the minimum number of characters needed to be removed from the string so that no two adjacent characters are the same. Problem Statement Given a string with characters 'A', 'B', and 'C', we need to remove the minimum number of characters to ensure all adjacent pairs are different. For example, in "AAB", we need to remove one 'A' to get "AB". Algorithm Approach The strategy is to iterate through the string and whenever ...
Read MoreHow to write a cell phone number in an international way using JavaScript?
When you have visitors from worldwide on your websites, it is a good idea to show things like a cell phone number according to international standards. So they can easily understand. We can use the International Public Telecommunication Numbering Format to represent the cell phone number in an international way. Also, it is represented by the 'E-164' format. We have given the syntax below to follow to write a cell phone number in an international way. [+] [country code] [local phone number] Users can see that the international phone number contains '+' initially ...
Read MoreHow to sort date array in JavaScript
Sorting arrays of dates is a common task in JavaScript. This tutorial shows how to sort an array containing date strings in ascending chronological order. Suppose we have an array that contains some dates like this: const arr = [ [ '02/13/2015', 0.096 ], [ '11/15/2013', 0.189 ], [ '05/15/2014', 0.11 ], [ '12/13/2013', 0.1285 ], [ '01/15/2013', 0.12 ], [ '01/15/2014', 0.11 ], [ '02/14/2014', 0.11 ], ...
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