Properly update an error's properties.

Features

- Prevents overriding error core properties (name,
message, etc.)
- Protects against prototype pollution
- Prevents overriding existing properties
- Copies another error's properties
- Can set properties as non-enumerable
- Preserves properties descriptors (enumerable, writable,
configurable, get/set)
- Exception-safe: this only throws syntax errors
- Strict TypeScript typing of the return value

Example

``js
import setErrorProps from 'set-error-props'

const error = new Error('one')
setErrorProps(error, { prop: true, message: 'two' })
console.log(error.prop) // true
console.log(error.message) // 'one': message is readonly
`

Install

`bash
npm install set-error-props
`

This package works in both Node.js >=18.18.0 and
browsers.

This is an ES module. It must be loaded using
an import or import() statement,
not require(). If TypeScript is used, it must be configured to
output ES modules,
not CommonJS.

API

setErrorProps(error, props, options?)

error Error | object\
props Error | object\
options Options?\
_Return value_: Error

Assigns props to error, then returns error.

$3

#### soft

_Type_: boolean\
_Default_: false

Prevents overriding existing properties.

Usage

Error core properties

`js
const error = new Error('one')
setErrorProps(error, { message: 'two' })
console.log(error.message) // 'one'
`

Prototype pollution

`js
const error = new Error('one')
setErrorProps(error, { toString: () => 'injected' })
console.log(error.toString()) // 'Error: one'
console.log(Error.prototype.toString()) // 'Error'
`

Overriding protection

`js
const error = new Error('message')
error.one = true
setErrorProps(error, { one: false, two: true }, { soft: true })
console.log(error.one) // true
console.log(error.two) // true
`

Error copy

`js
const error = new Error('one')
const secondError = new Error('two')
secondError.prop = true
setErrorProps(error, secondError)
console.log(error.message) // 'one'
console.log(error.prop) // true
`

Non-enumerable properties

`js
const error = new Error('message')

// Properties that start with _ are not enumerable
setErrorProps(error, { _one: true, two: true })

console.log(error._one) // true
console.log(error.two) // true
console.log(Object.keys(error)) // ['two']
console.log(error) // Prints two but not _one
`

Descriptors

`js
const error = new Error('message')
Object.defineProperty(error, 'prop', {
value: false,
enumerable: false,
writable: true,
configurable: true,
})
setErrorProps(error, { prop: true })
console.log(error.prop) // true
console.log(Object.getOwnPropertyDescriptor(error, 'prop').enumerable) // false
`

Exception safety

`js
const error = new Proxy(new Error('message'), {
set: () => {
throw new Error('example')
},
defineProperty: () => {
throw new Error('example')
},
})
setErrorProps(error, { prop: true }) // This does not throw
`

Related projects

- modern-errors: Handle errors in
a simple, stable, consistent way
- error-custom-class: Create
one error class
- error-class-utils: Utilities
to properly create error classes
- error-serializer: Convert
errors to/from plain objects
- normalize-exception:
Normalize exceptions/errors
- is-error-instance: Check if
a value is an Error instance
- set-error-class: Properly
update an error's class
- set-error-message: Properly
update an error's message
- wrap-error-message:
Properly wrap an error's message
- set-error-stack: Properly
update an error's stack
- merge-error-cause: Merge an
error with its cause
- error-cause-polyfill:
Polyfill error.cause
- handle-cli-error: 💣 Error
handler for CLI applications 💥
- log-process-errors: Show
some ❤ to Node.js process errors
- error-http-response:
Create HTTP error responses
- winston-error-format: Log
errors with Winston

Support

For any question, _don't hesitate_ to submit an issue on GitHub.

Everyone is welcome regardless of personal background. We enforce a
Code of conduct in order to promote a positive and
inclusive environment.

Contributing

This project was made with ❤️. The simplest way to give back is by starring and
sharing it online.

If the documentation is unclear or has a typo, please click on the page's Edit`
button (pencil icon) and suggest a correction.

If you would like to help us fix a bug or add a new feature, please check our
guidelines. Pull requests are welcome!