@stdlib/utils-some-own-by/README.md

Test whether some `own` properties of a provided object satisfy a predicate function for at least `n` properties.

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# someOwnBy

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> Test whether an object contains at least `n` own properties which pass a test implemented by a predicate function.

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<section class="intro">

</section>

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<section class="installation">

## Installation

```bash
npm install @stdlib/utils-some-own-by
```

</section>

<section class="usage">

## Usage

```javascript
var someOwnBy = require( '@stdlib/utils-some-own-by' );
```

#### someOwnBy( obj, n, predicate\[, thisArg ] )

Tests whether an `object` contains at least `n` own properties which pass a test implemented by a `predicate` function.

```javascript
function isNegative( value ) {
    return ( value < 0 );
}

var obj = {
    'a': 1,
    'b': -2,
    'c': 3,
    'd': -1
};

var bool = someOwnBy( obj, 2, isNegative );
// returns true
```

Once the function finds `n` successful properties, the function **immediately** returns `true`.

```javascript
function isPositive( value ) {
    if ( value < 0 ) {
        throw new Error( 'should never reach this line' );
    }
    return ( value > 0 );
}

var obj = {
    'a': 1,
    'b': 2,
    'c': -3,
    'd': 4
};

var bool = someOwnBy( obj, 2, isPositive );
// returns true
```

The invoked `function` is provided three arguments:

-   `value`: object property value
-   `key`: object property key
-   `obj`: input object

To set the function execution context, provide a `thisArg`.

```javascript
function sum( value ) {
    this.sum += value;
    this.count += 1;
    return ( value < 0 );
}

var obj = {
    'a': 1,
    'b': 2,
    'c': 3,
    'd': -5
};

var context = {
    'sum': 0,
    'count': 0
};

var bool = someOwnBy( obj, 1, sum, context );
// returns true

var mean = context.sum / context.count;
// returns 0.25
```

</section>

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

<section class="notes">

## Notes

-   An [`Object`][mdn-object] refers to a JavaScript object, which is a collection of properties. Each property is an association between a key (or name) and a value. The key can be a string or a symbol, and the value can be any JavaScript value, including functions and other objects

-   If provided an empty `object`, the function returns `false`.

    ```javascript
    function alwaysTrue() {
        return true;
    }
    var bool = someOwnBy( {}, 1, alwaysTrue );
    // returns false
    ```

-   The function does **not** skip `undefined` elements.

    <!-- eslint-disable no-sparse-arrays, stdlib/doctest-marker -->

    ```javascript
    function log( value, key ) {
        console.log( '%s: %s', key, value );
        return ( value < 0 );
    }

    var obj = {
        'a': 1,
        'b': void 0,
        'c': void 0,
        'd': 4,
        'e': -1
    };

    var bool = someOwnBy( obj, 1, log );
    /* =>
        a: 1
        b: void 0
        c: void 0
        d: 4
        e: -1
    */
    ```

-   The function provides limited support for dynamic objects (i.e., objects whose `length` changes during execution).

</section>

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<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random-base-randu' );
var someOwnBy = require( '@stdlib/utils-some-own-by' );

function threshold( value ) {
    return ( value > 0.95 );
}

var bool;
var obj = {};
var i;

for ( i = 0; i < 100; i++ ) {
    obj[ 'key'+i ] = randu();
}

bool = someOwnBy( obj, 5, threshold );
// returns <boolean>
```

</section>

<!-- /.examples -->

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</section>

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* * *

## See Also

</section>

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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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2024. The Stdlib [Authors][stdlib-authors].

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

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