ono

What is ono?

The 'ono' npm package is a utility for creating and managing errors in JavaScript. It allows you to create custom error messages, wrap existing errors, and add additional context to errors. This can be particularly useful for debugging and logging purposes.

What are ono's main functionalities?

Creating Custom Errors

This feature allows you to create custom error messages. The 'ono' function can be used to generate a new error with a specific message.

const ono = require('ono');

const error = ono('Something went wrong!');
console.error(error);

Wrapping Existing Errors

This feature allows you to wrap existing errors with additional context. This can be useful for adding more information to errors that are caught during execution.

const ono = require('ono');

try {
  JSON.parse('invalid JSON');
} catch (err) {
  const wrappedError = ono(err, 'Failed to parse JSON');
  console.error(wrappedError);
}

Adding Context to Errors

This feature allows you to add additional context to errors, such as custom properties. In this example, a status code is added to the error object.

const ono = require('ono');

const error = ono({ status: 404 }, 'Resource not found');
console.error(error);
console.error(error.status);

Other packages similar to ono

verror

The 'verror' package provides similar functionality for creating and managing errors. It allows you to create rich error objects with additional context and stack traces. Compared to 'ono', 'verror' offers more advanced features for error propagation and chaining.

create-error

The 'create-error' package is another alternative for creating custom error types. It allows you to define new error classes with custom properties and methods. While 'ono' focuses on wrapping and adding context to errors, 'create-error' is more about defining new error types.

custom-error-generator

The 'custom-error-generator' package allows you to generate custom error classes with specific properties and methods. It is similar to 'create-error' but offers more flexibility in defining the error structure. Compared to 'ono', it is more focused on error class generation rather than error wrapping and context.

README

ono (Oh No!)

Throw better errors.

Features

• Formatted error messages, using Node's util.format() or your own custom formatter
• Wrap and re-throw an error without losing the original error's message and stack trace
• Add custom properties to your errors — great for error codes, support numbers, help URLs, etc.
• Errors can be serialized as JSON, including all native and custom properties

Example

// Throw an error with formatted message
throw ono("%s is invalid. Must be at least %d characters.", username, minLength);

// Wrap and re-throw an error without losing the original error's message and stack
throw ono(err, "Unable to save account #%d", accountNumber);

// Throw an error with custom properties (even a custom method!)
throw ono({code: 413, status: "Invalid data", retry: function() {...}});

// Add custom properties to an existing Error
throw ono(err, {code: 413, status: "Invalid data", retry: function() {...}})

// Any of the above can be throw a specific Error type
throw ono.range(...);       // RangeError
throw ono.syntax(...);      // SyntaxError
throw ono.reference(...);   // ReferenceError

Installation

Node

Install using npm:

npm install ono

Then require it in your code:

var ono = require("ono");

Web Browsers

Install using bower:

bower install ono

Then reference ono.js or ono.min.js in your HTML:

<script src="bower_components/ono/dist/ono.js"></script>

Or, if you're using AMD (Require.js), then import it into your module:

define(["ono"], function(ono) { /* your module's code */ })

API

ono([err], [props], [message, ...])

Creates an Error object with the given properties.

• err - (optional) An existing error object. This error's message and stack trace will be appended to the new error.

• props - (optional) An object whose properties will be added to the new error. Properties can be anything, including objects and functions.

• message - (optional) The error message string. If it contains placeholders, then pass each placeholder's value as an additional parameter. See ono.formatter for more info.

Specific error types

The default ono() function always creates Error objects, but you can use any of the following methods to explicitly create the corresponding Error subclass. The method signatures are exactly the same as above.

Method	Error type
ono.error()	Error (this is just an alternate syntax)
ono.eval()	EvalError
ono.range()	RangeError
ono.reference()	ReferenceError
ono.syntax()	SyntaxError
ono.type()	TypeError
ono.uri()	URIError

ono.formatter

By default, Node's util.format() function is used (even in browsers) to format error messages and substitute placeholders with their corresponding values. You can set ono.formatter to a third-party formatter or even your own custom implementation, like this:

ono.formatter = function(message) {
    var params = Array.prototype.slice.call(arguments, 1);
    return params.reduce(function(message, param, index) {
        return message.replace("$" + index, param);
    }, message);
}

throw ono("$0 must be greater than $1", 4, 10);

Contributing

I welcome any contributions, enhancements, and bug-fixes. File an issue on GitHub and submit a pull request.

Building/Testing

To build/test the project locally on your computer:

1. Clone this repo
   git clone https://github.com/bigstickcarpet/ono.git

2. Install dependencies
   npm install

3. Run the build script
   npm run build

4. Run the unit tests
   npm run mocha (test in Node)
   npm run karma (test in web browsers)
   npm test (test in Node and browsers, and report code coverage)

License

Ono is 100% free and open-source, under the MIT license. Use it however you want.