Questions
HTML questions
Choose a question page, learn the concept, then test your understanding with a quiz.
How to Style a Select Dropdown with CSS Only
Learn what CSS can and cannot do when styling HTML select dropdowns, including browser limits, practical techniques, and fallbacks.
How to Style an iframe with CSS in HTML
Learn how CSS works with iframes, why parent page styles do not automatically apply, and practical ways to style iframe content safely.
How to Style an input type="file" Button in HTML and CSS
Learn how to style an HTML file input button using CSS, labels, and accessible patterns with practical examples.
How to Validate an Email Address in JavaScript
Learn how to validate an email address in JavaScript using simple checks, regex, and browser tools with beginner-friendly examples.
How to Vertically Align Elements in a div with CSS
Learn how to vertically align images and headings inside a div using modern CSS, including flexbox and absolute positioning.
How to Vertically Align Text in a div with CSS
Learn how vertical alignment works in CSS, why `vertical-align` does not center normal div text, and the best ways to center content.
How to Vertically Center Text with CSS
Learn how to vertically center text with CSS using flexbox, line-height, and other practical techniques for modern layouts.
How to Vertically Center a div in CSS Across Browsers
Learn practical CSS techniques to vertically center a div, including older browser limitations and reliable modern solutions.
How to Wrap Text in a pre Tag in HTML
Learn how to make text wrap inside an HTML pre tag using CSS while preserving whitespace and formatting for code and debug output.
JavaScript DOM Ready: Vanilla JS Equivalent of jQuery $(document).ready()
Learn the vanilla JavaScript equivalent of jQuery $(document).ready() using DOMContentLoaded, load, and safe cross-browser patterns.
JavaScript Links: Should You Use href="#" or javascript:void(0)?
Learn why href="#" and javascript:void(0) are usually poor choices, and what to use instead for JavaScript actions.
Local Storage vs Cookies in JavaScript: Key Differences and When to Use Each
Learn the real differences between cookies and localStorage in JavaScript, including performance, security, size, and best use cases.
Matching Opening HTML Tags with Regex in JavaScript
Learn how to match opening HTML tags while excluding self-closing tags, and understand the limits of regex for HTML parsing.
Select Elements by Data Attribute in jQuery
Learn how to select elements by data attributes in jQuery, including exact matches, syntax examples, mistakes, and practical use cases.
Up and Down Triangle Characters in HTML: Unicode Symbols and Entities
Learn how to display up and down triangle symbols in HTML using Unicode and entities, with examples, use cases, and common mistakes.
Using CSS content with HTML Entities in CSS
Learn how the CSS content property works, why HTML entities like do not render there, and how to insert characters correctly.
WebSockets vs Server-Sent Events (EventSource): Differences, Use Cases, and When to Choose Each
Learn the difference between WebSockets and Server-Sent Events, when to use each, and how browser-server communication works.
What Is a Clearfix in CSS? Understanding Float Clearing and Layout Behavior
Learn what a clearfix is in CSS, why floated elements affect parent layout, and how clearfix fixes collapsed containers with examples.
What X-UA-Compatible Does in HTML for Internet Explorer
Learn what the X-UA-Compatible meta tag does, when IE=edge matters, and why modern HTML pages usually should not use it.
What multipart/form-data Means in HTML Forms
Learn what enctype="multipart/form-data" means in HTML forms, when to use it, and how it affects file uploads and form submission.