Purpose:

catchAsync handles asynchronous errors in Express.js routes by catching rejected promises and passing them to the error-handling middleware.

Key Concepts:

• Higher-Order Function: Takes an async function and returns a new function that wraps it.

• Error Handling: Automatically catches errors and calls next(err) to pass them to Express error handlers.

Code Explanation:

const catchAsync = (fn: RequestHandler) => {
  return (req: Request, res: Response, next: NextFunction) => {
    Promise.resolve(fn(req, res, next)).catch(err => next(err));
  };
};

export default catchAsync;

Usage Example:

Instead of:

app.get('/example', async (req, res, next) => {
  try {
    // Async code
  } catch (err) {
    next(err);
  }
});

Use catchAsync:

app.get('/example', catchAsync(async (req, res, next) => {
  // Async code
}));

Benefits:

• Cleaner Code: Eliminates repetitive try-catch blocks.

• Consistency: Uniform error handling.

• Readability: More concise route handlers.