someOwnBy

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

Usage

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.

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

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>

someOwnBy

Usage

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

Notes

Examples

See Also