Default error handling for Express routes

express-error-handler.js

['get', 'post', 'put', 'delete'].forEach((method) => {
  const originalFn = app[method];
  app[method] = function fn(...args) {
    const routeFn = args[args.length - 1];
    const firstArgs = args.slice(0, args.length - 1);
    const newRouteFn = (req, res, next) => {
      try {
        if (routeFn.constructor.name === 'AsyncFunction') {
          return routeFn(req, res, next).catch(next);
        }
        return routeFn(req, res, next);
      } catch (err) {
        return next(err);
      }
    };
    return originalFn.call(this, ...firstArgs, newRouteFn);
  };
});

Example usage:

app.get('/test', (req, res) => {
  // undefined variable, will throw an error. normally, this can't be caught by any Express error handler, 
  // but our dirty little hack above will catch it.
  iAmUndefined;

  return res.send('wow');
});