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About stdlib...

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.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

someOwnBy

NPM version Build Status Coverage Status

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

Usage

import someOwnBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-some-own-by@esm/index.mjs';

The previous example will load the latest bundled code from the esm branch. Alternatively, you may load a specific version by loading the file from one of the tagged bundles. For example,

import someOwnBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-some-own-by@v0.1.0-esm/index.mjs';

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

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

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.

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.

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

Notes

  • An 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.

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

  • The function does not skip undefined elements.

    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).

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">

import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@esm/index.mjs';
import someOwnBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-some-own-by@esm/index.mjs';

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>

</script>
</body>
</html>

See Also

Notice

This package is part of stdlib, a standard library 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

Chat

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.