npm package: @stdlib/error-to-json
Description: Return a JSON representation of an error object.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
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</details>

# error2json

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Return a [JSON][json] representation of an [error][mdn-error] object.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/error-to-json
```

</section>

<section class="usage">

## Usage

```javascript
var error2json = require( '@stdlib/error-to-json' );
```

#### error2json( error )

Returns a [JSON][json] representation of an [`error`][mdn-error] object.

```javascript
var err = new Error( 'beep' );

var json = error2json( err );
/* e.g., returns
    {
        'type': 'Error',
        'name': 'Error', // if present
        'message': 'beep',
        'stack': '...' // if present
    }
*/
```

The [JSON][json] `object` is **guaranteed** to have the following properties:

-   **type**: error type.
-   **message**: error message.

The **only** standardized cross-platform property is `message`. Depending on the platform, the following properties **may** be present:

-   **name**: error name.
-   **stack**: stack trace.
-   **code**: error code ([Node.js][node-system-error] system errors).
-   **errno**: error code `string` ([Node.js][node-system-error] system errors).
-   **syscall**: `string` representing the failed system call ([Node.js][node-system-error] system errors).

The function also serializes **all** `enumerable` properties.

<!-- eslint-disable object-curly-newline -->

```javascript
var err = new Error( 'beep' );
err.a = 'b';
err.c = { 'd': 'e' };

var json = error2json( err );
/* e.g., returns
    {
        'type': 'Error',
        'name': 'Error', // if present
        'message': 'beep',
        'stack': '...', // if present
        'a': 'b',
        'c': {
            'd': 'e'
        }
    }
*/
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   Supported built-in [`error`][mdn-error] types:

    -   [`Error`][mdn-error]
    -   [`TypeError`][mdn-type-error]
    -   [`SyntaxError`][mdn-syntax-error]
    -   [`ReferenceError`][mdn-reference-error]
    -   [`RangeError`][mdn-range-error]
    -   [`URIError`][mdn-uri-error]
    -   [`EvalError`][mdn-eval-error]

-   The implementation supports custom error types and sets the `type` field to the closest built-in [`error`][mdn-error] type.

    ```javascript
    function CustomError( msg ) {
        this.name = 'CustomError';
        this.message = msg || '';
        this.stack = ( new TypeError() ).stack;
        return this;
    }
    CustomError.prototype = Object.create( TypeError.prototype );
    CustomError.prototype.constructor = CustomError;

    var err = new CustomError( 'boop' );

    var json = error2json( err );
    /* e.g., returns
        {
            'type': 'TypeError',
            'name': 'CustomError',
            'message': 'boop',
            'stack': '...'
        }
    */
    ```

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var error2json = require( '@stdlib/error-to-json' );

var err = new Error( 'beep' );
var out = error2json( err );
/* e.g., returns
    {
        'type': 'Error',
        'name': 'Error',
        'message': 'beep',
        'stack': '...'
    }
*/

err = new TypeError( 'invalid type' );
out = error2json( err );
/* e.g., returns
    {
        'type': 'TypeError',
        'name': 'TypeError',
        'message': 'invalid type',
        'stack': '...'
    }
*/

err = new SyntaxError( 'bad syntax' );
out = error2json( err );
/* e.g., returns
    {
        'type': 'SyntaxError',
        'name': 'SyntaxError',
        'message': 'bad syntax',
        'stack': '...'
    }
*/

err = new ReferenceError( 'unknown variable' );
out = error2json( err );
/* e.g., returns
    {
        'type': 'ReferenceError',
        'name': 'ReferenceError',
        'message': 'unknown variable',
        'stack': '...'
    }
*/

err = new URIError( 'bad URI' );
out = error2json( err );
/* e.g., returns
    {
        'type': 'URIError',
        'name': 'URIError',
        'message': 'bad URI',
        'stack': '...'
    }
*/

err = new RangeError( 'value out-of-range' );
out = error2json( err );
/* e.g., returns
    {
        'type': 'RangeError',
        'name': 'RangeError',
        'message': 'value out-of-range',
        'stack': '...'
    }
*/

err = new EvalError( 'eval error' );
out = error2json( err );
/* e.g., returns
    {
        'type': 'EvalError',
        'name': 'EvalError',
        'message': 'eval error',
        'stack': '...'
    }
*/
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

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<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/error-reviver`][@stdlib/error/reviver]</span><span class="delimiter">: </span><span class="description">revive a JSON-serialized error object.</span>

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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<section class="links">

[npm-image]: http://img.shields.io/npm/v/@stdlib/error-to-json.svg
[npm-url]: https://npmjs.org/package/@stdlib/error-to-json

[test-image]: https://github.com/stdlib-js/error-to-json/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/error-to-json/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/error-to-json/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/error-to-json?branch=main

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[stdlib]: https://github.com/stdlib-js/stdlib

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/error-to-json/tree/deno
[deno-readme]: https://github.com/stdlib-js/error-to-json/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/error-to-json/tree/umd
[umd-readme]: https://github.com/stdlib-js/error-to-json/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/error-to-json/tree/esm
[esm-readme]: https://github.com/stdlib-js/error-to-json/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/error-to-json/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/error-to-json/main/LICENSE

[json]: http://www.json.org/

[mdn-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error

[mdn-type-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError

[mdn-syntax-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SyntaxError

[mdn-range-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RangeError

[mdn-reference-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ReferenceError

[mdn-uri-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/URIError

[mdn-eval-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/EvalError

[node-system-error]: https://nodejs.org/api/errors.html#errors_class_system_error

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[@stdlib/error/reviver]: https://www.npmjs.com/package/@stdlib/error-reviver

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