The Ultimate Guide: Fixing the `navigator.clipboard` is undefined Error in Local JavaScript Development

Encountering the `Uncaught TypeError: Cannot read properties of undefined (reading 'writeText')` error when implementing a copy-to-clipboard feature in your local development environment? This isn't due to a missing library but is a result of the browser's Secure Context policy. This article dives into the root cause, shows you how to verify your environment, and provides two core solutions: enabling HTTPS for your local server (like a dev environment for wiki.lib00.com) or implementing an elegant fallback to a legacy API.