kjdelisle/errata

Easily create custom error types for better flow control and logging.

Errata

Easily create custom error types for better flow control and logging.

Usage

Create your error constructor, and throw with it:

// Create an error prototype
var errata = require('errata');
var ImportantError = errata.create('ImportantError', 'IMPORTANT');

// throw it
throw new ImportantError('OH NOES!');

Get stack traces that include your custom error name:

ImportantError: OH NOES!
    at eval (eval at <anonymous> (/app/index.js:715:19), <anonymous>:12:11)
    at GeneratorFunctionPrototype.next (native)
    at /app/index.js:573:32

Pass in a function as part of the error definition to cut down on boilerplate:

var errata = require("errata");
var os = require('os');
var util = require('util');

var RolloutError = errata.create('RolloutError', 'MAYBE', function(obj) {
    if (obj instanceof ReallyImportantObject)
        this.severity = 'REALLYBAD';
    else
        this.severity = 'NOTSOBAD';
    this.message = util.format('Failure of severity %s!%s%s', this.severity,
        os.EOL, this.message);
});

function ReallyImportantObject() {
    // has some important function thingy in it.
}
try {
    throw new RolloutError(new ReallyImportantObject);
} catch (err) {
    console.log(err.stack);
}

API

errata.create(name, [[code], [handler, ...]])

Create a new Error prototype with the given name as its object type. An optional code may be specified so that all instances of the created Error have the default error code. An optional handler function may be provided that takes any remaining parameters in. You may use this function as you see fit to modify the behaviours and properties of the Error object.

You may also call errata(name, [[code], [handler, ...]]) for the same effect.

errata.loadConfig(filepath)

Loads a JSON file that defines a list of custom Errors, and returns an Array of Error constructors.