The weakest spots in the JS code I have seen, in npm and the projects I've had to maintain: - Profiling CPU and memory: preventing and mitigating resource leak

The weakest spots in the JS code I have seen, in npm and the projects I've had to maintain: - Profiling CPU and memory: preventing and mitigating resource leaks. - Robustness: Input validation, error handling, logging. - Event handling and construction of finite state machines: defining states and transitions and validating them. - Using a sane coding standard. Like Google's JS standard rather than the self proclaimed "standard" from feross. The "request" npm module for example, is a FSM where states are defined by a combination of flags. However you can obtain states that are not handled by the library, because the FSM is constructed poorly without validating state transitions. That is a very common theme in npm modules.