PrettyMonitor

PrettyMonitor is a small debug utility that catches escaped when.js rejections in node.js apps and renders them in a readable format.

Screenshot

This is similar to when.js's default monitoring tool: when/monitor/console. Here is a screenshot of the original tool (as of when-3.1):

PrettyMonitor does the same thing with some formatting:

Usage (in when-3.x)

Install with npm:

npm install pretty-monitor

And in your javascript:

// require the dependencies first:
wn = require('when');
PrettyMonitor = require('pretty-monitor');
PromiseMonitor = require('when/monitor/PromiseMonitor');

// then, instantiate the monitor:
promiseMonitor = new PromiseMonitor(new PrettyMonitor());

// ... and start it:
promiseMonitor.monitor(wn.Promise);

// to see a sample rejection:
wn().then(function(){
	// this will throw an error and cause a rejection which won't be handled.
	// PrettyMonitor will log this rejection to the console.
	someNonExistingFunction();
});

Note on when-3.1

The monitoring api on when-3.1 looks a tiny bit different:

// require the dependencies first:
wn = require('when');
PrettyMonitor = require('pretty-monitor');
PromiseMonitor = require('when/monitor/PromiseMonitor');

// this is the different part:
console.promiseMonitor = new PromiseMonitor(new PrettyMonitor());

// to see a sample rejection:
wn().then(function(){
	// this will throw an error and cause a rejection which won't be handled.
	// PrettyMonitor will log this rejection to the console.
	someNonExistingFunction();
});

Usage (in when-2.x)

Install with npm:

npm install [email protected]

And then require it somewhere in your code:

require('pretty-monitor').start();

// to see a sample rejection:
var wn = require('when');
require('pretty-monitor').start();

wn().then(function(){
	// this will throw an error and cause a rejection which won't be handled.
	// PrettyMonitor will log this rejection to the console.
	someNonExistingFunction();
});

Customization

PrettyMonitor uses PrettyError to render the rejections. PrettyError is very customizable. You can set themes, customize layout and colors, and simplify the stack trace. There are a bunch of examples at PrettyError's docs, so, make sure to check them out.

To access the PrettyError instance when using PrettyMonitor:

prettyError = prettyMonitor.getPrettyError();

// if you're using [email protected]:
prettyError = prettyMonitor.start();

State of The Project

This is a work in progress. I'll try to fix bugs and keep it up-to-date with when.js. Feel free to open an issue if something isn't working, and of course, Pull Requests are more than welcome :)

License

MIT