Custom Error Factory

custom-error-factory is an open source module that exposes a factory function to create instantiable custom error classes, extending native error types.

Using custom error classes allows you to store more information,a nd in a clearer way, than in a standard object. This can make custom errors easier to retrieve and analyse once being logged.

Install with the command npm install custom-error-factory

Creating a custom error class

You can create a custom error type using the function customErrorFactory, which returns the constructor of the custom error class.

//built-in error class to inherit from
var type = TypeError;

//custom error name
var name = 'Invalid_Delay_Granularity_Error';

//custom error message (can be overwritten at the instance level)
var defaultMessage = 'This is not a recognized time period. Try: \'seconds\', \'minutes\', \'hours\'.';

var InvalidDelayGranularityError = customErrorFactory(type,
	name,
	defaultMessage);

You can then create an instance of this custom error class:

var e = new InvalidDelayGranularityHRError();

You can pass additional properties to the constructor:

var obj = {
	foo: 'bar'
};

var e = new InvalidDelayGranularityError(obj);

You can also overwrite the default message:

var e = new InvalidDelayGranularityHRError('overwritten message');

And also overwrite the default message and pass additional properties at the same time:

var obj = {
	foo: 'bar'
};

var e = new InvalidDelayGranularityHRError(obj, 'overwritten message');

Tests

The test spec is in /test/test.spec.js, and the test suite is jasmine-node, which you can install by running npm install -g jasmine-node

You can run the tests with the commands jasmine-node test or npm run test

To do

Perhaps some integration with an error logging library? This would be a good way to leverage the extra information that can be stored in a custom error object.

Thank you for reading this far. If you have any bugs to report or improvements to suggest you can send me an email at [email protected].