ErrorPlus

Have you ever gotten an error like ECONNREFUSED and thought "gee this application makes 3 or 4 connections, this error doesn't really tell me what is failing." ErrorPlus is an attempt to provide the syntactical sugar needed to properly capture and format errors spanning across complex asynchronous workflows. This should result in making it easy to build up detailed errors as they propagate back up the call stack from deep in the bowels of the V8 system libraries.

Trivial Example

var ErrorPlus = module.require('./ErrorPlus');

var error1 = new ErrorPlus('IllegalOperation', 'Permission denied.');
var error2 = new ErrorPlus(error1, 'FileNotFound', 'Could not open the file "%s".', '/tmp/logs/process-20000101000000.log');
var error3 = new ErrorPlus(error2, 'InternalFailure', 'Unable to write log entry.');

console.log(error3.format());

The format function produces a very readable string that could easily be included in a single error log entry.

InternalFailure: Unable to write log entry.
    at Object.<anonymous> (C:\Users\Eric\WebstormProjects\nostradamus\datalayer\source\ErrorPlus-spec.js:5:14)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)
    at startup (node.js:129:16)
    at node.js:814:3
FileNotFound: Could not open the file "/tmp/logs/process-20000101000000.log".
    at Object.<anonymous> (C:\Users\Eric\WebstormProjects\nostradamus\datalayer\source\ErrorPlus-spec.js:4:14)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)
    at startup (node.js:129:16)
    at node.js:814:3
IllegalOperation: Permission denied.
    at Object.<anonymous> (C:\Users\Eric\WebstormProjects\nostradamus\datalayer\source\ErrorPlus-spec.js:3:14)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)
    at startup (node.js:129:16)
    at node.js:814:3

Async Example

In a real async workflow, each stack trace would potentially be from a different call stack. If you are careful to enhance the error before you callback with it, you can get a much better top down view of what happened. Towards the top of the stack should be your application's messages and towards the bottom will be frustrating V8 system errors like ENOENT and ECONNREFUSED.

somethingAsync(function (error) {
    if (error) {

        // Rather than just propagating the error, we enhance it, adding more and more detail.
        callback(new ErrorPlus(error, 'EnhancedType', 'Enhanced error message about what is happening here.'););
    }
})

Enjoy!

The MIT License (MIT)

Copyright (c) 2015 Eric Rini

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
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The above copyright notice and this permission notice shall be included in
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