npm package: @stdlib/assert-is-read-only-property
Description: Test if an object's own property is read-only.
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>

# isReadOnlyProperty

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

> Test if an object's own property is [read-only][@stdlib/utils/define-read-only-property].

<section class="installation">

## Installation

```bash
npm install @stdlib/assert-is-read-only-property
```

</section>

<section class="usage">

## Usage

```javascript
var isReadOnlyProperty = require( '@stdlib/assert-is-read-only-property' );
```

#### isReadOnlyProperty( value, property )

Returns a `boolean` indicating if a `value` has a [read-only][@stdlib/utils/define-read-only-property] `property`.

<!-- eslint-disable no-restricted-syntax -->

```javascript
var defineProperty = require( '@stdlib/utils-define-property' );

var obj = {
    'foo': 'bar'
};

defineProperty( obj, 'beep', {
    'configurable': false,
    'enumerable': false,
    'writable': false,
    'value': 'boop'
});

defineProperty( obj, 'accessor', {
    'configurable': false,
    'enumerable': true,
    'get': function getter() {
        return obj.foo;
    }
});

var bool = isReadOnlyProperty( obj, 'foo' );
// returns false

bool = isReadOnlyProperty( obj, 'beep' );
// returns true

bool = isReadOnlyProperty( obj, 'accessor' );
// returns true
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   Value arguments other than `null` or `undefined` are coerced to `objects`.

    ```javascript
    var bool = isReadOnlyProperty( 'beep', 'length' );
    // returns true
    ```

-   Property arguments are coerced to `strings`.

    ```javascript
    var defineProperty = require( '@stdlib/utils-define-property' );

    var obj = {};

    defineProperty( obj, 'null', {
        'configurable': false,
        'enumerable': true,
        'writable': false,
        'value': true
    });

    var bool = isReadOnlyProperty( obj, null );
    // returns true
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

```javascript
var isReadOnlyProperty = require( '@stdlib/assert-is-read-only-property' );

var bool = isReadOnlyProperty( 'a', 'length' );
// returns true

bool = isReadOnlyProperty( { 'a': 'b' }, 'a' );
// returns false

bool = isReadOnlyProperty( [ 'a' ], 0 );
// returns false

bool = isReadOnlyProperty( { 'null': false }, null );
// returns false

bool = isReadOnlyProperty( { '[object Object]': false }, {} );
// returns false

bool = isReadOnlyProperty( {}, 'toString' );
// returns false

bool = isReadOnlyProperty( {}, 'hasOwnProperty' );
// returns false

bool = isReadOnlyProperty( null, 'a' );
// returns false

bool = isReadOnlyProperty( void 0, 'a' );
// returns false
```

</section>

<!-- /.examples -->

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

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/assert-is-read-only-property-in`][@stdlib/assert/is-read-only-property-in]</span><span class="delimiter">: </span><span class="description">test if an object's own or inherited property is read-only.</span>
-   <span class="package-name">[`@stdlib/assert-is-read-write-property`][@stdlib/assert/is-read-write-property]</span><span class="delimiter">: </span><span class="description">test if an object's own property is readable and writable.</span>
-   <span class="package-name">[`@stdlib/assert-is-readable-property`][@stdlib/assert/is-readable-property]</span><span class="delimiter">: </span><span class="description">test if an object's own property is readable.</span>
-   <span class="package-name">[`@stdlib/assert-is-writable-property`][@stdlib/assert/is-writable-property]</span><span class="delimiter">: </span><span class="description">test if an object's own property is writable.</span>

</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 -->

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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/assert-is-read-only-property/tree/deno
[deno-readme]: https://github.com/stdlib-js/assert-is-read-only-property/blob/deno/README.md
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[branches-url]: https://github.com/stdlib-js/assert-is-read-only-property/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/assert-is-read-only-property/main/LICENSE

[@stdlib/utils/define-read-only-property]: https://www.npmjs.com/package/@stdlib/utils-define-read-only-property

<!-- <related-links> -->

[@stdlib/assert/is-read-only-property-in]: https://www.npmjs.com/package/@stdlib/assert-is-read-only-property-in

[@stdlib/assert/is-read-write-property]: https://www.npmjs.com/package/@stdlib/assert-is-read-write-property

[@stdlib/assert/is-readable-property]: https://www.npmjs.com/package/@stdlib/assert-is-readable-property

[@stdlib/assert/is-writable-property]: https://www.npmjs.com/package/@stdlib/assert-is-writable-property

<!-- </related-links> -->

</section>

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