npm package: @stdlib/assert-is-read-only-property-in
Description: Test if an object's own or inherited property is read-only.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
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</details>

# isReadOnlyPropertyIn

[![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 or inherited property is [read-only][@stdlib/utils/define-read-only-property].

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### isReadOnlyPropertyIn( 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 bool;
var obj;

function Foo() {
    this.foo = 'bar';
    return this;
}

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

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

obj = new Foo();

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

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

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

</section>

<!-- /.usage -->

<section class="notes">

## Notes

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

    ```javascript
    var bool = isReadOnlyPropertyIn( '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 = isReadOnlyPropertyIn( obj, null );
    // returns true
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

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

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

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

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

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

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

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

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

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

bool = isReadOnlyPropertyIn( 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`][@stdlib/assert/is-read-only-property]</span><span class="delimiter">: </span><span class="description">test if an object's own property is read-only.</span>
-   <span class="package-name">[`@stdlib/assert-is-read-write-property-in`][@stdlib/assert/is-read-write-property-in]</span><span class="delimiter">: </span><span class="description">test if an object's own and inherited property is readable and writable.</span>
-   <span class="package-name">[`@stdlib/assert-is-readable-property-in`][@stdlib/assert/is-readable-property-in]</span><span class="delimiter">: </span><span class="description">test if an object's own or inherited property is readable.</span>
-   <span class="package-name">[`@stdlib/assert-is-writable-property-in`][@stdlib/assert/is-writable-property-in]</span><span class="delimiter">: </span><span class="description">test if an object's own or inherited 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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[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-in/tree/deno
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/assert-is-read-only-property-in/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]: https://www.npmjs.com/package/@stdlib/assert-is-read-only-property

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

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

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

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