Questions
HTML questions
Choose a question page, learn the concept, then test your understanding with a quiz.
How to Scroll a Div to the Bottom in JavaScript for Chat UIs
Learn how to scroll a div to the bottom in JavaScript, including auto-scroll behavior after AJAX updates in chat interfaces.
How to Select Elements by Name in jQuery
Learn how to select elements by name in jQuery using attribute selectors, with examples, mistakes to avoid, and practical use cases.
How to Select an Element with Multiple Classes in jQuery
Learn how to select elements with multiple classes in jQuery using combined class selectors, examples, mistakes, and real use cases.
How to Set Email Subject and Body with mailto: Links
Learn how to use mailto: links to prefill email subject and body, including syntax, examples, limitations, and common mistakes.
How to Set Table Cell Padding and Spacing in CSS
Learn how to replace HTML table cellpadding and cellspacing with modern CSS using padding and border-spacing.
How to Set a Default Selected Option in an HTML Select Element
Learn how to set the default selected option in an HTML select element using selected, option values, and JavaScript.
How to Store Arrays in localStorage with JavaScript
Learn how to save and retrieve JavaScript arrays in localStorage using JSON.stringify and JSON.parse, with practical examples and pitfalls.
How to Store JavaScript Objects in localStorage and sessionStorage
Learn why localStorage stores strings only and how to safely save and retrieve JavaScript objects using JSON.stringify and JSON.parse.
How to Style a Checkbox Using CSS
Learn why checkbox styling is limited by default and how to customize checkboxes with CSS using practical beginner-friendly examples.
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.
Include One HTML File in Another HTML File
Learn how to reuse HTML content in another page using iframes, server-side includes, templates, and JavaScript fetch patterns.
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.