Build a Live Character Counter for Text Areas

A live character counter is one of those small UI details that makes a big difference in usability. When users know how many characters they have left — and can see that number updating as they type — they write with more confidence and hit submit without guessing whether their input is too long. Twitter … Read more

How to Show and Hide a Password Field with JavaScript

The show/hide password toggle is one of the most useful small interactions you can add to a login or signup form. Typing a complex password into a masked field and then guessing whether you made a typo is frustrating. One button fixes it entirely. The implementation is genuinely simple — just a few lines of … Read more

How to Validate a Form with Plain JavaScript (No Libraries)

Form validation libraries are useful for complex applications. But for most contact forms, signup pages, and checkout flows, plain JavaScript gives you everything you need — and no extra dependencies, no bundle size cost, and no abstraction layer between you and what is actually happening. This guide builds a complete, production-ready form validator from scratch. … Read more

How to Validate an Email Address in JavaScript (With Working Code)

Email validation is one of those tasks that seems straightforward until you start thinking about edge cases. What about plus signs in addresses? Subdomains? International top-level domains? Two-letter country codes? The honest answer is that truly complete email validation is remarkably complex — the full RFC 5322 specification runs to dozens of pages. But for … Read more

How to Build a Countdown Timer with JavaScript

A countdown timer is one of those projects that teaches you a surprising amount. It covers working with dates, interval timing, DOM manipulation, and the kind of edge case handling that makes the difference between a timer that works and one that breaks at midnight on New Year’s Eve. Let’s build one from scratch — … Read more

How to Convert a String to a Number in JavaScript

Converting strings to numbers is something every JavaScript developer does constantly. User input always comes in as a string. API responses sometimes return numbers wrapped in quotes. Form fields give you text even when the user typed a digit. JavaScript gives you several ways to make the conversion — each with different behavior, different edge … Read more

How to Round Numbers to 2 Decimal Places in JavaScript

Rounding numbers to two decimal places comes up constantly in JavaScript — calculating prices, displaying currency, handling user input, processing form data. JavaScript gives you several ways to do it, and each one behaves slightly differently depending on your use case. This guide covers every method worth knowing, when to use each one, and the … Read more