https://github.com/necojackarc/extensible-custom-error
JavaScript extensible custom error that can take a message and/or an Error object
https://github.com/necojackarc/extensible-custom-error
ecmascript error error-handling javascript node
Last synced: about 2 months ago
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JavaScript extensible custom error that can take a message and/or an Error object
- Host: GitHub
- URL: https://github.com/necojackarc/extensible-custom-error
- Owner: necojackarc
- License: mit
- Created: 2018-10-07T16:16:12.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2024-11-18T23:05:09.000Z (about 1 year ago)
- Last Synced: 2025-04-13T02:16:34.965Z (8 months ago)
- Topics: ecmascript, error, error-handling, javascript, node
- Language: JavaScript
- Homepage: https://www.npmjs.com/package/extensible-custom-error
- Size: 693 KB
- Stars: 95
- Watchers: 4
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# Extensible Custom Error
[](https://coveralls.io/github/necojackarc/extensible-custom-error?branch=master)
[](https://badge.fury.io/js/extensible-custom-error)
JavaScript extensible custom error that can take a message and/or an Error object
```js
class MyError extends ExtensibleCustomError {}
new MyError('message'); // Take a message
new MyError(error); // Take an error
new MyError('message', error); // Take a message and an error
```
## Contents
- [Extensible Custom Error](#extensible-custom-error)
- [Contents](#contents)
- [Features](#features)
- [Define custom errors easily](#define-custom-errors-easily)
- [Wrap errors without losing any data](#wrap-errors-without-losing-any-data)
- [Installation](#installation)
- [Usage](#usage)
- [Define custom errors](#define-custom-errors)
- [Instantiate custom errors](#instantiate-custom-errors)
- [Examples](#examples)
- [Wrap an error](#wrap-an-error)
- [Wrap an error while passing a new message](#wrap-an-error-while-passing-a-new-message)
- [Special Thanks](#special-thanks)
- [License](#license)
## Features
There are some pains around JavaScript error handling.
Two of them are:
1. Define custom errors easily
2. Wrap errors without losing any data
This `ExtensibleCustomError` class enables you to do both - you can define your custom errors easily and wrap errors with them while merging stack traces prettily.
### Define custom errors easily
To define custom errors in Vanilla JS, you need to set names and stack traces manually, but you no longer need to do that with `ExtensibleCustomError`.
```js
class MyError extends ExtensibleCustomError {}
```
### Wrap errors without losing any data
Built-in errors only take a message, so they can't wrap any errors, which means stack traces so far will be lost.
However, `ExtensibleCustomError` can take a message and/or an Error object while merging stack traces.
```js
catch (error) {
throw new MyError(error);
}
```
```js
catch (error) {
throw new MyError('message', error);
}
```
## Installation
Using npm:
```bash
$ npm install extensible-custom-error
```
## Usage
### Define custom errors
```js
// CommonJS
const ExtensibleCustomError = require('extensible-custom-error');
// ESM
// import ExtensibleCustomError from 'extensible-custom-error';
// That's it!
class MyError extends ExtensibleCustomError {}
```
```js
// Should you need to set custom properties
class MyErrorWithCustomProperty extends ExtensibleCustomError {
constructor(...args) {
// Ensure calling the super constructor
super(...args);
Object.defineProperty(this, 'customProperty', {
configurable: true,
enumerable : false,
value : 'I am the Bone of my Sword',
writable : true,
});
}
}
```
N.B. With an uglifier, class names might get obsecure. See [this issue comment](https://github.com/bjyoungblood/es6-error/issues/31#issuecomment-301128220).
### Instantiate custom errors
You can instantiate your custom errors in the same way as built-in errors.
```js
// Throw it as usual!
throw new MyError('Steel is my Body and Fire is my Blood');
```
```js
try {
// Do something that may cause errors
} catch (error) {
// Pass an error instance, then stack traces will be merged
throw new MyError(error);
}
```
```js
try {
// Do something that may cause errors
} catch (error) {
// Pass a message and an error instance, then stack traces will be merged
throw new MyError('I have created over a Thousand Blades', error);
}
```
## Examples
### Wrap an error
If you run:
```js
const ExtensibleCustomError = require('extensible-custom-error');
class MyError extends ExtensibleCustomError {}
function throwBuiltinError() {
throw new Error('Unknown to Death, Nor known to Life');
}
function wrapErrorWithMyError() {
try {
throwBuiltinError();
} catch (error) {
throw new MyError(error);
}
}
function main() {
try {
wrapErrorWithMyError();
} catch (error) {
console.log(error);
}
}
main();
```
you'll get:
```bash
MyError: Error: Unknown to Death, Nor known to Life
at wrapErrorWithMyError (/home/necojackarc/custom_error.js:101:11)
Error: Unknown to Death, Nor known to Life
at throwBuiltinError (/home/necojackarc/custom_error.js:94:9)
at wrapErrorWithMyError (/home/necojackarc/custom_error.js:99:5)
at main (/home/necojackarc/custom_error.js:107:5)
at Object. (/home/necojackarc/custom_error.js:113:1)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Function.Module.runMain (module.js:693:10)
```
### Wrap an error while passing a new message
If you run:
```js
const ExtensibleCustomError = require('extensible-custom-error');
class MyError extends ExtensibleCustomError {}
function throwBuiltinError() {
throw new Error('Have withstood Pain to create many Weapons');
}
function wrapErrorWithMyError() {
try {
throwBuiltinError();
} catch (error) {
throw new MyError('Unlimited Blade Works', error);
}
}
function main() {
try {
wrapErrorWithMyError();
} catch (error) {
console.log(error);
}
}
main();
```
you'll get:
```bash
MyError: Unlimited Blade Works
at wrapErrorWithMyError (/home/necojackarc/custom_error.js:101:11)
Error: Have withstood Pain to create many Weapons
at throwBuiltinError (/home/necojackarc/custom_error.js:94:9)
at wrapErrorWithMyError (/home/necojackarc/custom_error.js:99:5)
at main (/home/necojackarc/custom_error.js:107:5)
at Object. (/home/necojackarc/custom_error.js:113:1)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Function.Module.runMain (module.js:693:10)
```
## Special Thanks
* [@yszk0123](https://github.com/yszk0123) as a reviewer
* [bjyoungblood/es6-error](https://github.com/bjyoungblood/es6-error) as a reference
## License
The module is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).