better-custom-error

DEPRECATED

This library is deprecated. Use @ezez/errors instead.

better-custom-error

Helper for creating Error subclass with bonus features. It fully works as expected with code transpiled to ES5 from ES6 code. It allows to pass custom data to errors and it contains features useful for logging/debugging.

Reasons to use

• Cleaner code.

  • Custom error types makes code more readable and easier to maintenance. They can inherit from built-in or other custom types and instanceof works as expected with multi level inheritance.
  • A lot of developers uses custom properties for storing additional data. But usually it not uniform and requires three lines of code to create, extend and throw your error. With this library you're guided on the details object property name and it's easy to throw with details on single line.
  • Ability to throw new error type basing on already created instance of another error. Did you get an error with details from inner method, want to handle it and pass more generic error outside? You can do that!

• Easy to use

  • Custom errors behaves just like standard errors when used without extra features.
  • No more painstaking building error message string with multiple variables. Just throw meaningful message and pass details as an object.
  • No more JSON serializing data into error message. - Yeah, I've seen that.
  • Custom error doesn't care about arguments order. It will figure it out. Pass parent error instance, message and details object in any order. Pass null or undefined and it won't crash, so you don't need to care about variable/property existence/initialization check.

• Enables better logging and bug tracking:

  • You can access inheritance tree from your error.
  • Node.js internal stack trace lines are removed, focus on the code itself (you can disable this feature).

Usage

Full documentation of latest deprecated version is available here: documentation.

yarn add better-custom-error or npm i better-custom-error --save

import { createError } from "better-custom-error";
// or const { createError } = require("better-custom-error");

const MyError = createError("MyError");
const AnotherError = createError("AnotherError", MyError); // it extends `Error` by default, but you can pass another error
const YetAnotherError = createError("YetAnotherError", Error, options);

For options see: Options Usage.

Imporant: creating two errors with the same name will create two different errors references anyway! Export them and import where needed or make your errors global.

Note on TypeScript

This library is basically all about creating new types on runtime. TypeScript is static typechecker, therefore it doesn't play perfect with this, because every error has basically the same type, optionally differentiating on details object shape.

See documentation for more info.

TODO

• Further memory optimization:
  • create and extend one Custom Error instance
  • use getters to delay some calculations from error creation to actual read place
• Ability to override Error prototype so some better-custom-error features will be available on native errors too
• extend method for easier extending

License

MIT