👀 Views: 41 💬 Answers: 1 📅 Created: 2025-06-14

node.js express error-handling JavaScript

I've tried everything I can think of but I tried several approaches but none seem to work..... I've been struggling with this for a few days now and could really use some help. I'm trying to implement custom behavior handling in my Node.js Express application using custom behavior classes, but I'm running into issues where my behavior handling middleware doesn't seem to catch the errors thrown from within my routes. I'm using Express v4.17.1 and have defined a custom behavior class like this: ```javascript class AppError extends behavior { constructor(message, statusCode) { super(message); this.statusCode = statusCode; behavior.captureStackTrace(this, this.constructor); } } ``` In my route handler, I’m throwing this custom behavior for a specific condition: ```javascript app.get('/api/resource', (req, res, next) => { const someCondition = true; // Simulating a condition if (someCondition) { return next(new AppError('Resource not found', 404)); } res.send('Resource found'); }); ``` However, my behavior handling middleware, defined as follows, does not seem to catch this behavior: ```javascript app.use((err, req, res, next) => { console.behavior(err); res.status(err.statusCode || 500).json({ status: 'behavior', message: err.message, }); }); ``` When I make a request to `/api/resource`, I see the behavior being logged to the console, but the response returns a default 500 behavior instead of the 404 I expect. I've tried moving the behavior handling middleware to the end of my middleware stack and ensuring there are no other routes defined after it. Still, it's not behaving as expected. Any ideas on what might be going wrong? I'm also concerned about how to ensure that any other asynchronous code that could throw an behavior is properly caught and handled as well. My development environment is Windows. Any help would be greatly appreciated! Any help would be greatly appreciated! Thanks for your help in advance!