Just a collection of interesting questions on StackOverflow, the programmer’s greatest online Q&A source.

JavaScript

• How to detect caps lock?
• How to validate numbers?
• How to copy to the clipboard?
• How to validate emails?
• How to pretty-print JSON?
• How to check if a checkbox is checked?
• You cannot comment JSON files
• The difference between == and ===
• How to check if one string contains another string?
• How to check if a DOM element exists?
• How to test if a DOM element is visible?
• How to tell apart left/right click?
• How to hide a div when you click outside of it?
• A practical explanation of JavaScript closures
• How to get the current URL of the page
• document.createElement … in jQuery
• How to empty an array
• What does !! mean?
• How to detect if JavaScript is disabled
• Calling JavaScript code in an iframe
• How to get dimensions of web page, screen, and browser?
• Playing sound in JavaScript
• How to test whether the browser window is currently visible?
• How to add minutes to time?
• How to add hours to time?
• Textarea maxlength attribute emulation

HTML/CSS

• Keep parents of floating elements from collapsing
• Center a div in a div
• <b> vs. <strong>, <i> vs. <em>
• Changing input placeholder text color with CSS
• Clarifying relative URLs in CSS
• Fill the remaining page height with a div
• Style a dropdown with just CSS
• Should I use button or input type="button"?
• Disable text selection highlighting
• How to set cellpadding and cellspacing?
• What clearfix should I use?
• Applying CSS to an iframe
• Align content to bottom of a div
• Simulating float: bottom
• You cannot write :hover inline
• Dynamically changing website favicon
• Style: why do we use dashes for ids and classes?

PHP

• What does ___ mean in PHP?
• How to prevent SQL injection
• Get the first element of an array
• require_once vs. include
• Performance of === vs. ==

Java

• Declaring an inline array
• What is “uses unckeched or unsafe”?

Misc.

• Commenting in Markdown