error3

Error3 is an Error with extra powers. It has been designed to be extensible and easy to use.
Though it has codes, message formatters and nested errors.

* Modern: designed for TypeScript and ES2019.
* IDE friendly: it's using classes and class fields to be inspectable for autosuggetion tools.
* i18n ready: formatter could produce localized messages with help of Intl API.
* Easy serialization and deserealization: good for network apps and JSON logging.
* Frontend caring: 0 dependencies, gzipped version is less then 1 KiB.

Table of Contents

* Install
* Usage
* Examples
* API

Install

* In node.js:
``bash
npm i error3
`
* In browser:
`html

`
CommonJS ·
UMD ·
ESM
> ⚠️ Remember about security! Add subresource integrity (SRI) checksum
> from checksum.txt.

Usage

Error3 suppose that you will create some base error class for your application
or library and then use it as a parent for all your errors. Watch example in
examples folder. Here it is interface realization:

`javascript
import Error3 from 'error3'

class NotFoundErr extends Error3 {
code = 'fs_not_found'

format({filepath}) {
return File "${filepath}" not found
}
}
`

This is what it gives to us:

`javascript
const error = new NotFoundErr({filepath: './index.js'});
error.toString() // -> "NotFoundErr: [#fs_not_found] File "./index.js" not found"
error.message // -> "File "./index.js" not found"
error.code // -> fs_not_found
error.details // -> {filepath: './index.js'}
`

The same error TypeScript implementation:

`typescript
import Error3 from 'error3'

class NotFoundErr extends Error3<{filepath: string}, void> {
code = 'fs_not_found'

format({filepath}): string {
return File "${filepath}" not found
}
}
`

$3

Calling Error3#toJSON() on Error3 instance returns an object with properties
code, message, details, and errors. Example output:

`json
{
"code": "fs_not_found",
"message": "File \"./index.js\" not found",
"details": {
"filepath": "./index.js"
},
"errors": []
}
`

Examples

* HTTP errors JS · TS
* FileSystem errors JS · TS
* Localized I18n error messages JS · TS

API

$3

`text
(details:object = {}, errors:Error[] = []) -> Error3
`

__abstract__. Both of Error3 constructor arguments are optional. The resposibility of
ancestor class is to implement proper interface and pass details object
and errors list into super() call.

details is using to describe error with JS primitives. Though it could be sent
via network to frontend, db, or ELK without extra parsing as it should be done
with regular Error instance.

#### TS Interface

`typescript
abstract class Error3 extends Error implements IError3 {
public readonly code: string|number
public readonly name: string
public readonly details: object
public readonly errors: Error[]

constructor(details: Details, errors: Errors) {}
abstract format(detials: Details, errors: Errors): string
}
`

#### Example

`javascript
const error = new UserMissed(
{userId: 1}, [new Error('Collection removed')]
);

error.code // -> user_missed
error.message // -> User #1 not loaded
error.details // -> {userId: 1}
error.errors // -> [Error('Collection removed')]
`

$3


`
string|number
`

Error code should be a string or a number. It could be defined using class fields
syntax:

`javascript
class HttpNotFound extends HttpError {
code = 404
}
`

$3


`
(details: object, errors: Error[]) -> string
`

__abstract__. Creates formatted message string from details and other errors.
This method is calling from Error3 constrcutor to define message property.

#### JS
`javascript
class PortInUse extends Error3 {
format({port}) {
return Port ${port} is already in use
}
}
`

#### TS
`typescript
class PortInUse extends Error3<{port: string|number}, void> {
format({port}): string {
return Port ${port} is already in use
}
}
`

$3

Wrapper of Error3#valueOf. It's created to be used by JSON.stringify().

$3


`
() -> PlainError
`

This method realizes Object#valueOf() behavior and returns plain error object containing properties:
code, message, details and errors.

$3


`
{
code: string|number,
message: string,
details: object,
errors: PlainError[],
}
`

It is a result of Error3#valueOf()` call.

License

MIT © Rumkin