@stdlib/utils-for-own
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    0.0.7 • Public • Published

    forOwn

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    Invoke a function for each own enumerable property of an object.

    Installation

    npm install @stdlib/utils-for-own

    Usage

    var forOwn = require( '@stdlib/utils-for-own' );

    forOwn( obj, fcn[, thisArg ] )

    Invokes a function for each own enumerable property of an object.

    function log( value, key ) {
        console.log( '%s: %d', key, value );
    }
    
    var obj = {
        'a': 1,
        'b': 2,
        'c': 3,
        'd': 4
    };
    
    forOwn( obj, log );
    /* e.g., =>
        a: 1
        b: 2
        c: 3
        d: 4
    */

    The invoked function is provided three arguments:

    • value: object property value
    • key: object property
    • obj: the input object

    To terminate iteration before visiting all properties, the provided function must explicitly return false.

    function log( value, key ) {
        console.log( '%s: %d', key, value );
        return false;
    }
    
    var obj = {
        'a': 1,
        'b': 2,
        'c': 3,
        'd': 4
    };
    
    forOwn( obj, log );
    // e.g., => a: 1

    To set the function execution context, provide a thisArg.

    function sum( value ) {
        this.sum += value;
        this.count += 1;
    }
    
    var obj = {
        'a': 1,
        'b': 2,
        'c': 3,
        'd': 4
    };
    
    var context = {
        'sum': 0,
        'count': 0
    };
    
    forOwn( obj, sum, context );
    
    var mean = context.sum / context.count;
    // returns 2.5

    Notes

    • The function returns the input object.
    • The function determines the list of own enumerable properties before invoking the provided function. Hence, any modifications made to the input object after calling this function (such as adding and removing properties) will not affect the list of visited properties.
    • Property iteration order is not guaranteed.

    Examples

    var fromCodePoint = require( '@stdlib/string-from-code-point' );
    var forOwn = require( '@stdlib/utils-for-own' );
    
    function update( value, key, obj ) {
        console.log( '%s: %d', key, value );
        obj[ key ] *= value;
    }
    
    var obj;
    var key;
    var i;
    
    obj = {};
    for ( i = 0; i < 26; i++ ) {
        key = fromCodePoint( 97 + i );
        obj[ key ] = i;
    }
    
    forOwn( obj, update );
    console.log( obj );

    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.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2021. The Stdlib Authors.

    Install

    npm i @stdlib/utils-for-own

    Homepage

    stdlib.io

    DownloadsWeekly Downloads

    2

    Version

    0.0.7

    License

    Apache-2.0

    Unpacked Size

    39.6 kB

    Total Files

    9

    Last publish

    Collaborators

    • stdlib-bot
    • kgryte
    • planeshifter
    • rreusser