Symbol which specifies a method for converting an object to a primitive value.
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> [Symbol][mdn-symbol] which specifies a method for converting an object to a primitive value.
``bash`
npm install @stdlib/symbol-to-primitive
`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'
- 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.'string'
- If the hint is , the method should return a string.'default'
- If the hint is , 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.
`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
`
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[stdlib]: https://github.com/stdlib-js/stdlib
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[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