flinger

Flinger flings logs from your browser clients back to your node servers so you can see what your users are up to.

Why Care?

Web applications, and single page applications in particular, make it hard to see errors that are happening in client side JavaScript.

What It Does

Flinger flings logs from your browser clients back to your node servers so you can see what your users are up to.

What It Is

Flinger is node middleware for express or connect that does two things:

  • For the client, serves a client library that monkey patches
    • console.log
    • console.error
    • Error
  • For the server, provides a receiver that catches and logs client logs

How To Use It

Flinger uses jQuery for HTTP back to the server. Make sure it is in your page.

Here is the most basic installation possible:

var express = require('connect');
var app = connect()
    .use(connect.cookieParser())
    .use(connect.static(path.join(__dirname, 'client')))
    .use(flinger())
    .listen(9999);

Flinger serves its client library automatically as a convenience, so on the client:

<script type="text/javascript" src="/flinger.js"></script>

This redirects, by default:

  • client console.log(...) to server console.log(...)
  • client console.error(...) to server console.error(...)
  • client new Error(...) to server console.error(...)

Flinger lets you hook to reformat or log as you see fit, flinger really is:

flinger(onConsoleLog, onConsoleError, onException)

Each of the onXXX functions is:

function handler(logEvent){}

Each logEvent is:

  • request, flinger logs over HTTP, so you can get at cookies etc to identify users and make custom logs
  • arguments, the javascript arguments captured on the client function