npm package: @stdlib/symbol-to-primitive
Description: Symbol which specifies a method for converting an object to a primitive value.
Author: The Stdlib Authors
Latest version: 0.1.2

<!--

@license Apache-2.0

Copyright (c) 2025 The Stdlib Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

-->


<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>
  <p>The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.</p>
  <p>When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.</p>
  <p>To join us in bringing numerical computing to the web, get started by checking us out on <a href="https://github.com/stdlib-js/stdlib">GitHub</a>, and please consider <a href="https://opencollective.com/stdlib">financially supporting stdlib</a>. We greatly appreciate your continued support!</p>
</details>

# ToPrimitiveSymbol

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

> [Symbol][mdn-symbol] which specifies a method for converting an object to a primitive value.

<!-- 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/symbol-to-primitive
```

</section>

<section class="usage">

## Usage

```javascript
var ToPrimitiveSymbol = require( '@stdlib/symbol-to-primitive' );
```

#### ToPrimitiveSymbol

[Symbol][mdn-symbol] which specifies a method for converting an object to a primitive value.

```javascript
var s = typeof ToPrimitiveSymbol;
// e.g., returns 'symbol'
```

</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

-   The [symbol][mdn-symbol] is only supported in environments which support [symbols][mdn-symbol]. In non-supporting environments, the value is `null`.

-   When an object needs to be converted to a primitive value, JavaScript runtimes look for a `[ToPrimitiveSymbol]()` method on the object. If the method exists, JavaScript runtimes call the method with a `hint` string argument (one of `'number'`, `'string'`, or `'default'`) indicating the preferred type of the primitive value to be returned.

    -   If the hint is `'number'`, the method should return a number.
    -   If the hint is `'string'`, the method should return a string.
    -   If the hint is `'default'`, the method can return either a number or a string.

-   If an object does not have a `[ToPrimitiveSymbol]()` method, JavaScript runtimes use the default type conversion algorithm by calling `valueOf()` and/or `toString()` methods.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint-disable no-invalid-this -->

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

```javascript
var defineProperty = require( '@stdlib/utils-define-property' );
var Number = require( '@stdlib/number-ctor' );
var ToPrimitiveSymbol = require( '@stdlib/symbol-to-primitive' );

function CustomObject( value ) {
    if ( !(this instanceof CustomObject) ) {
        return new CustomObject( value );
    }
    this._value = value;
    return this;
}

function toPrimitive( hint ) {
    var value = this._value;
    if ( hint === 'string' ) {
        return 'CustomObject: ' + value;
    }
    if ( hint === 'number' ) {
        return value;
    }
    // Default hint:
    return value;
}

defineProperty( CustomObject.prototype, ToPrimitiveSymbol, {
    'configurable': false,
    'enumerable': false,
    'writable': false,
    'value': toPrimitive
});

var obj = new CustomObject( 42 );

console.log( String( obj ) );
// => 'CustomObject: 42'

console.log( Number( obj ) );
// => 42

console.log( obj + 10 );
// => 52
```

</section>

<!-- /.examples -->

<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<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>

<!-- /.stdlib -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

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

[test-image]: https://github.com/stdlib-js/symbol-to-primitive/actions/workflows/test.yml/badge.svg?branch=v0.1.2
[test-url]: https://github.com/stdlib-js/symbol-to-primitive/actions/workflows/test.yml?query=branch:v0.1.2

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

<!--

[dependencies-image]: https://img.shields.io/david/stdlib-js/symbol-to-primitive.svg
[dependencies-url]: https://david-dm.org/stdlib-js/symbol-to-primitive/main

-->

[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com

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

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

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

</section>

<!-- /.links -->