examples/error/index.js

   1 'use strict'
   2
   3 /**
   4  * Module dependencies.
   5  */
   6
   7 var express = require('../../');
   8 var logger = require('morgan');
   9 var app = module.exports = express();
  10 var test = app.get('env') === 'test'
  11
  12 if (!test) app.use(logger('dev'));
  13
  14 // error handling middleware have an arity of 4
  15 // instead of the typical (req, res, next),
  16 // otherwise they behave exactly like regular
  17 // middleware, you may have several of them,
  18 // in different orders etc.
  19
  20 function error(err, req, res, next) {
  21   // log it
  22   if (!test) console.error(err.stack);
  23
  24   // respond with 500 "Internal Server Error".
  25   res.status(500);
  26   res.send('Internal Server Error');
  27 }
  28
  29 app.get('/', function () {
  30   // Caught and passed down to the errorHandler middleware
  31   throw new Error('something broke!');
  32 });
  33
  34 app.get('/next', function(req, res, next){
  35   // We can also pass exceptions to next()
  36   // The reason for process.nextTick() is to show that
  37   // next() can be called inside an async operation,
  38   // in real life it can be a DB read or HTTP request.
  39   process.nextTick(function(){
  40     next(new Error('oh no!'));
  41   });
  42 });
  43
  44 // the error handler is placed after routes
  45 // if it were above it would not receive errors
  46 // from app.get() etc
  47 app.use(error);
  48
  49 /* istanbul ignore next */
  50 if (!module.parent) {
  51   app.listen(3000);
  52   console.log('Express started on port 3000');
  53 }