npm package: @stdlib/array-base-cuany-by
Description: Cumulatively test whether at least one element in a provided array passes a test implemented by a predicate function.
Author: The Stdlib Authors
Latest version: 0.1.1

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# cuanyBy

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

> Cumulatively test whether at least one element in a provided array passes a test implemented by a predicate function.

<section class="installation">

## Installation

```bash
npm install @stdlib/array-base-cuany-by
```

</section>

<section class="usage">

## Usage

```javascript
var cuanyBy = require( '@stdlib/array-base-cuany-by' );
```

#### cuanyBy( x, predicate\[, thisArg] )

Cumulatively tests whether at least one element in a provided array passes a test implemented by a `predicate` function.

```javascript
function isPositive( value ) {
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];

var y = cuanyBy( x, isPositive );
// returns [ false, false, false, true, true ]
```

The `predicate` function is provided three arguments:

-   **value**: current array element.
-   **index**: current array element index.
-   **arr**: input array.

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

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

var x = [ 0, 0, 0, 1, 0 ];

var context = {
    'count': 0
};

var out = cuanyBy( x, isPositive, context );
// returns [ false, false, false, true, true ]

var cnt = context.count;
// returns 4
```

#### cuanyBy.assign( x, out, stride, offset, predicate\[, thisArg] )

Cumulatively tests whether at least one element in a provided array passes a test implemented by a `predicate` function and assigns results to a provided output array.

```javascript
function isPositive( value ) {
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];
var y = [ false, null, false, null, false, null, false, null, false, null ];

var out = cuanyBy.assign( x, y, 2, 0, isPositive );
// returns [ false, null, false, null, false, null, true, null, true, null ]

var bool = ( out === y );
// returns true
```

The function supports the following parameters:

-   **x**: input array.
-   **out**: output array.
-   **stride**: output array stride.
-   **offset**: output array offset.
-   **predicate**: test function.

</section>

<!-- /.usage -->

<section class="notes">

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var bernoulli = require( '@stdlib/random-array-bernoulli' );
var cuanyBy = require( '@stdlib/array-base-cuany-by' );

function isPositive( value ) {
    return ( value > 0 );
}

// Create an array of random values:
var x = bernoulli( 10, 0.1 );
console.log( x );

// Cumulatively determine whether at least one element is positive:
var out = cuanyBy( x, isPositive );
console.log( out );
```

</section>

<!-- /.examples -->

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<section class="related">

</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

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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