Memory leaks in JavaScript don't announce themselves with an error. They show up as a heap that grows by 20MB per minute — invisible in a five-minute Lighthouse run, fatal in a six-hour production session. Why React apps leak: A useEffect that opens a WebSocket and never closes it on unmount. A setInterval without clearInterval in the cleanup return. A global Map that grows without bound. In each
A few years ago I solved 200 LeetCode problems and still froze on Mediums I hadn't seen. The breakthrough wasn't another hundred problems. It was a different loop. A problem asks for the longest substring with at most K distinct characters. You've solved sliding window before. Maximum sum subarray of size K, done. Longest substring without repeating characters, done. This third one stalls you. Twe