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Error Handling and Debugging @ stefanprodan/timoni 

## Strategies and methods for error handling and debugging in Timoni (https://github.com/stefanprodan/timoni)
      
      ### What is Error Handling and Debugging?
      
      Error handling and debugging are essential practices in software development to identify and resolve issues that prevent correct program execution. In the context of the Timoni project, error handling refers to the mechanisms and techniques used to manage and respond to unexpected conditions or exceptions during runtime. Debugging, on the other hand, is the process of identifying and fixing the root cause of issues in the codebase.
      
      ### Why is Error Handling and Debugging important?
      
      Effective error handling and debugging are crucial for maintaining the reliability, security, and performance of software applications. By implementing proper error handling strategies, developers can:
      
      1. Improve user experience by providing clear and helpful error messages.
      2. Prevent application crashes and data loss.
      3. Ensure application security by handling potential vulnerabilities and attacks.
      4. Facilitate faster issue resolution and development.
      
      ## Strategies and methods for error handling in Timoni
      
      ### Centralized Error Handling
      
      Timoni uses a centralized error handling approach, which allows developers to manage errors in a consistent and efficient manner. This approach involves defining a custom error class or interface and using it throughout the application to handle errors.
      
      ```javascript
      // Custom error class
      class CustomError extends Error {
      constructor(message, statusCode) {
      super(message);
      this.statusCode = statusCode;
      }
      }
      
      // Error handling middleware
      const errorHandler = (err, req, res, next) => {
      const statusCode = err.statusCode || 500;
      res.status(statusCode).json({ message: err.message });
      };
      
      // Application error handling
      app.use((err, req, res, next) => {
      errorHandler(err, req, res, next);
      });

Logging

Logging is an essential tool for error handling and debugging. Timoni uses the winston library for logging, which provides flexible and extensible logging functionality.

// Logging middleware
      const logger = require('winston');
      const winston = require('winston');
      
      const loggerInstance = winston.createLogger({
      level: 'info',
      format: winston.format.json(),
      transports: [
      new winston.transports.Console(),
      new winston.transports.File({ filename: 'error.log', level: 'error' })
      ]
      });
      
      app.use((req, res, next) => {
      loggerInstance.info(`${req.method} request received for ${req.url}`);
      next();
      });
      
      app.use((err, req, res, next) => {
      loggerInstance.error(err.message);
      next(err);
      });

Testing

Testing is an essential part of error handling and debugging. Timoni uses Jest as the testing framework, which provides extensive testing capabilities and integrates well with other tools and libraries.

// Testing error handling
      describe('Error handling', () => {
      it('should return a 500 status code and error message for an invalid route', async () => {
      const response = await request(app).get('/invalid-route');
      expect(response.statusCode).toBe(500);
      expect(response.body.message).toBe('Route not found');
      });
      });

Strategies and methods for debugging in Timoni

Breakpoints

Timoni supports debugging using breakpoints, which allow developers to pause the execution of the code and inspect the state of variables and the call stack. This can be done using the built-in debugger in Node.js or using a third-party debugging tool like Chrome DevTools.

// Debugging using Node.js debugger
      const debug = require('debug')('app:main');
      
      function handleRequest(req, res) {
      debug('Request received: %j', req);
      // Breakpoint here
      const data = processRequest(req);
      res.send(data);
      }
      
      app.get('/', handleRequest);
      
      // Debugging using Chrome DevTools
      const url = 'http://localhost:3000';
      const port = 3000;
      const sourceMapSupport = require('source-map-support').install();
      sourceMapSupport.install();
      
      chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
      if (request.command === 'debug') {
      chrome.devtools.inspectedWindow.eval(`debugger;`);
      }
      });
      
      const server = app.listen(port, () => {
      console.log(`Server listening on port ${port}`);
      });

Console.log

Console.log is a simple yet powerful debugging tool that allows developers to print information to the console during runtime. This can be used to inspect variables, check the flow of the code, and identify issues.

function processRequest(req) {
      console.log('Request received:', req);
      // Process request here
      return 'Hello, World!';
      }
      
      app.get('/', (req, res) => {
      const data = processRequest(req);
      res.send(data);
      });

Profiling

Profiling is the process of measuring the performance of the code and identifying bottlenecks. Timoni uses the clinic library for profiling, which provides detailed performance analysis and visualization capabilities.

const Clinic = require('clinic');
      const clinic = new Clinic();
      
      function processRequest(req) {
      // Performance measurement
      const start = clinic.time('processRequest');
      // Process request here
      const data = 'Hello, World!';
      const end = clinic.timeEnd('processRequest');
      console.log(`processRequest took ${end - start}ms`);
      return data;
      }
      
      app.get('/', (req, res) => {
      const data = processRequest(req);
      res.send(data);
      });
      
      clinic.printReport();

References

Explanation