Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Economics & Finance
JavaScript provides several methods to toggle class names on HTML elements. The most efficient approach is using the classList.toggle() method, which automatically adds a class if it doesn't exist or removes it if it does. Using classList.toggle() Method The toggle() method is the simplest way to switch between adding and removing a class: .highlight { background-color: #3498db; ... Read More
Let's say, we have an array that contains the score of some players in different sports. The scores are represented like this − const scores = [ {sport: 'cricket', aman: 54, vishal: 65, jay: 43, hardik: 88, karan:23}, {sport: 'soccer', aman: 14, vishal: 75, jay: 41, hardik: 13, karan:73}, {sport: 'hockey', aman: 43, vishal: 35, jay: 53, hardik: 43, karan:29}, {sport: 'volleyball', aman: 76, vishal: 22, jay: 36, hardik: 24, karan:47}, {sport: 'baseball', aman: 87, vishal: 57, jay: 48, hardik: 69, karan:37}, ]; We need to ... Read More
You can filter and display students with percentage more than 70% using various JavaScript approaches. This is useful for grade-based filtering and reporting. Following are the records of each student: const studentDetails = [ { studentName: "John", percentage: 78 }, { studentName: "Sam", percentage: 68 }, ... Read More
In JavaScript, variables declared inside a function are scoped to that function and cannot be directly accessed from outside. However, there are several ways to make these variables available to other functions or globally. Problem with Function Scope Variables declared inside a function are private to that function: function myFunction() { let localVar = "I'm inside the function"; } myFunction(); // console.log(localVar); // This would cause an error Using Constructor Functions with 'this' You can use constructor functions to expose internal variables as properties: const num ... Read More
In this tutorial, we will learn regular expressions to match numbers only in JavaScript. Data validation is essential for web applications. We often need to ensure users provide correct input — for example, phone numbers should contain only digits, or credit card fields should accept numbers only. Regular expressions provide a powerful way to validate and extract numeric data from strings. They use patterns to match specific character types and return the matched results. Understanding Regular Expression Patterns A regular expression consists of a pattern and optional modifiers. For matching numbers, we use: \d ... Read More
JavaScript provides two timing functions: setTimeout() for one-time execution and setInterval() for repeated execution at specified intervals. setTimeout() Function setTimeout(function, delay) executes a function once after a specified delay in milliseconds. Syntax setTimeout(function, delay); setTimeout(callback, delay, param1, param2, ...); Example setTimeout(function() { console.log('This runs once after 2 seconds'); }, 2000); console.log('This runs immediately'); This runs immediately This runs once after 2 seconds setInterval() Function setInterval(function, delay) executes a function repeatedly at specified intervals until ... Read More
In JavaScript, when an empty object {} is converted to a string, it becomes "[object Object]". This happens because JavaScript calls the object's toString() method during string conversion. How Object to String Conversion Works JavaScript follows these steps when converting an object to a string: First, it calls the object's toString() method For plain objects, toString() returns "[object Object]" This is the default string representation for all plain objects Example: Converting Empty Object to String Convert {} to String ... Read More
Convert videos to proper formats for HTML5 video on Linux shell using ffmpeg. HTML5 video requires specific codecs for cross-browser compatibility. MP4 with H.264/AAC works in most browsers, while OGV with Theora/Vorbis supports Firefox and other open-source browsers. Converting to MP4 Format When converting to MP4, use the H.264 video codec and AAC audio codec for maximum browser compatibility, especially IE11 and earlier versions. ffmpeg -i input.mov -vcodec h264 -acodec aac -strict -2 output.mp4 This command converts input.mov to output.mp4 with H.264 video and AAC audio codecs. MP4 with Maximum Compatibility ... Read More
This article presents a comprehensive Graph class implementation in JavaScript with various graph algorithms including traversal, shortest path, and minimum spanning tree algorithms. Graph Class Structure The Graph class uses an adjacency list representation with two main properties: nodes - Array storing all graph vertices edges - Object mapping each node to its connected neighbors with weights Basic Graph Operations const Queue = require("./Queue"); const Stack = require("./Stack"); const PriorityQueue = require("./PriorityQueue"); class Graph { constructor() { this.edges = {}; ... Read More
We need to write a function that accepts a string and mirrors its alphabet. This means each letter is replaced with its counterpart from the opposite end of the alphabet. If the input is 'abcd' The output should be 'zyxw' The function maps every character to the letter that is (26 - N) positions away from it, where N is the 1-based index of that alphabet (like 5 for 'e' and 10 for 'j'). How It Works We use the String.prototype.replace() method to match all English alphabets regardless of case. For each letter: ... Read More