express-error-log-handler

Express middleware-like error handler that takes care of your response status codes and messages.

Getting Started

Installation

$ npm install --save express-error-log-handler

Usage

express-error-log-handler works like any express middleware:

var express = require('express');
var errorHandler = require('express-error-log-handler');
    
const app = express();

// define routes
    
app.use(errorHandler(function(err) {
    console.log(err);
}));

app.listen(port);

// 💪 Works with es modules as well

*Make sure you use() the express-error-log-handler after you define all the routes.

Logging

The handler receives a log callback function which is called with the error details. The callback function receives an object containing:

• err.statusCode

  Type: number | ranges 400 ~ 599

  The HTTP status code that was sent as a response. for example:

  err.statusCode <- 500

• err.message

  Type: string

  The message that wes passed to the thrown error:

  err.message <- 'id 15 was not found'

• err.stack

  Type: string

  The full stackTrace generated by the error:

  err.stack <- 'Error: Forbidden
                    at Object.test (...\express-error-log-handler\__tests__\status-code.test.js:50:13)
                    at Object.asyncJestTest (...\express-error-log-handler\node_modules\install.js:102:37)
                    at resolve (...\express-error-log-handler\node_modules\build\queueRunner.js:43:12)
                    at new Promise (<anonymous>)
                    at mapper (...\express-error-log-handler\node_modules\build\queueRunner.js:26:19)
                    at promise.then (...\express-error-log-handler\node_modules\build\queueRunner.js:73:41)'

Response

The middleware creates a response for the client according to the HTTP standard.

status-code

Will be generated according to:

• Specified code:

// error constructor library - *recommended*
app.get(function (req, res, next) {
  if (!req.auth) {
    return next(createError(401))                  // -> will result a res.status(401)
  }
  next()
});

// the status-code itself
var err = new Error('User not found');
err.status = 404;

throw err;                                         // -> will result a res.status(404)

// the error title
var err = new Error('Internal Server Error');

throw err;                                         // -> will result a res.status(500)

*Check out http-errors for error creation

• Unspecified:

var err = new Error('User not found');
err.status = 404;                                  // -> will result a default res.status(500)

Message

res.message will always contain the status code's official description:

next(createError(500, 'invalid secret {...}'))     // -> res.message = 'Internal Server Error'

*while the log gets the "real" message

Production

The response is suitable for either non-production (like development/test) or production environments:

• For non-production (process.env.NODE_ENV !== production) :
  • Stack-trace will be included in the HTTP response.
  • Error of any code will be logged (including 400~499).
• For production (process.env.NODE_ENV === production)
  • Stack-track will be excluded in the HTTP response.
  • Only 500+ status codes will be logged.

*It is important to make sure process.env.NODE_ENV is set accordingly.

Suggestions 🤝

feel free to suggest any improvement or notify of any issue