anyBy

Test whether at least one element in an array passes a test implemented by a predicate function.

Installation

npm install @stdlib/array-base-any-by

Usage

var anyBy = require( '@stdlib/array-base-any-by' );

anyBy( x, predicate[, thisArg] )

Tests whether at least one element in an array passes a test implemented by a predicate function.

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

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

var bool = anyBy( x, isPositive );
// returns true

If a predicate function returns a truthy value, the function immediately returns false.

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

var x = [ -1, -2, -3, -4 ];

var bool = anyBy( x, isPositive );
// returns false

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.

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

var x = [ -1, -2, 3, -4 ];

var context = {
    'count': 0
};

var bool = anyBy( x, predicate, context );
// returns true

var cnt = context.count;
// returns 3

Notes

• If provided an array-like object having a some method (as defined by the ECMAScript Standard), the function defers execution to that method and assumes that the method API has the following signature:

  x.some( predicate, thisArg )

• If provided an array-like object without a some method, the function performs a linear scan and returns immediately upon encountering a truthy return value. Unlike Array.prototype.some, when performing a linear scan, the function does not skip undefined elements.

• If provided an empty array, the function returns false.

Examples

var bernoulli = require( '@stdlib/random-array-bernoulli' );
var isPositiveInteger = require( '@stdlib/assert-is-positive-integer' ).isPrimitive;
var naryFunction = require( '@stdlib/utils-nary-function' );
var anyBy = require( '@stdlib/array-base-any-by' );

var x = bernoulli( 10, 0.1, {
    'dtype': 'int8'
});
// returns <Int8Array>

var out = anyBy( x, naryFunction( isPositiveInteger, 1 ) );
// returns <boolean>

Notice

This package is part of 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, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.