Web Accessibility

Here's a solid reference for implementing WCAG 2.1 accessibility patterns. You get working examples for common ARIA patterns like modals and navigation menus, a focus trap implementation that handles Tab and Escape keys properly, and form validation with aria-invalid and role="alert". The color contrast section includes actual functions to calculate luminance ratios, which is helpful when you need to programmatically check if colors meet AA standards. It also shows you how to set up axe-core for automated testing. The examples are React/TypeScript heavy, so if you're working in vanilla JS or another framework you'll need to adapt the patterns, but the ARIA attributes and keyboard handling logic translate directly.