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    This package has been deprecated

    Author message:

    This module was renamed to error-custom-class.

    error-type
    TypeScript icon, indicating that this package has built-in type declarations

    3.0.0 • Public • Published

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    Create custom error types.

    Features

    Examples

    Custom error types

    import errorType from 'error-type'
    
    const UserError = errorType('UserError')
    const DatabaseError = errorType('DatabaseError')
    
    try {
      throw new UserError('message')
    } catch (error) {
      console.log(error.name) // 'UserError'
      console.log(error instanceof UserError) // true
    }

    Error properties

    const userError = new UserError('message', { props: { userId: 56 } })
    console.log(userError.userId) // 56

    Error cause

    // `error.cause` can be used even in older Node.js or browsers
    try {
      doSomething()
    } catch (cause) {
      throw new UserError('message', { cause })
    }

    Custom initialization logic

    const DatabaseError = errorType('DatabaseError', (error, { props }) => {
      error.dbId = props.databaseId
    })
    const databaseError = new DatabaseError('message', { props: { databaseId: 2 } })
    console.log(databaseError.dbId) // 2
    console.log(databaseError.databaseId) // undefined

    Install

    npm install error-type

    This package is an ES module and must be loaded using an import or import() statement, not require().

    API

    errorType(errorName, onCreate?)

    errorName string
    onCreate (error, params) => void
    Return value: CustomError

    Custom initialization logic

    onCreate(error, params) is optional and is called on new CustomError('message', params).

    By default, it sets any params.props as error properties. However, you can override it with any custom logic to validate, normalize params, etc.

    Best practices

    Constructor

    A common pattern for custom error types is:

    class CustomError extends Error {
      constructor(message) {
        super(message)
        this.name = 'CustomError'
      }
    }

    However, this has several issues (which error-type handles):

    • error.cause is not set
    • Unlike native error types, error.name is:
      • Enumerable, although it should not. For example, for (const key in error) will iterate over name, which is unexpected.
      • Set on the error instance instead of its prototype. In Node.js, this sometimes results in the error name being printed as Error [CustomError] instead of CustomError.

    Polyfills

    Some Error polyfills (such as es-shims/error-cause) prevent extending from it. This library includes some logic to fix this.

    Related projects

    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!

    Install

    npm i error-type

    DownloadsWeekly Downloads

    46

    Version

    3.0.0

    License

    Apache-2.0

    Unpacked Size

    25 kB

    Total Files

    8

    Last publish

    Collaborators

    • ehmicky