@stdlib/utils-every-by
    TypeScript icon, indicating that this package has built-in type declarations

    0.0.7 • Public • Published

    everyBy

    NPM version Build Status Coverage Status dependencies

    Test whether all elements in a collection pass a test implemented by a predicate function.

    Installation

    npm install @stdlib/utils-every-by

    Usage

    var everyBy = require( '@stdlib/utils-every-by' );

    everyBy( collection, predicate[, thisArg ] )

    Tests whether all elements in a collection pass a test implemented by a predicate function.

    function isPositive( value ) {
        return ( value > 0 );
    }
    
    var arr = [ 1, 2, 3, 4 ];
    
    var bool = everyBy( arr, isPositive );
    // returns true

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

    function isPositive( value ) {
        return ( value > 0 );
    }
    
    var arr = [ 1, -2, 3, 4 ];
    
    var bool = everyBy( arr, isPositive );
    // returns false

    The invoked function is provided three arguments:

    • value: collection element
    • index: collection index
    • collection: input collection

    To set the function execution context, provide a thisArg.

    function sum( value ) {
        if ( value < 0 ) {
            return false;
        }
        this.sum += value;
        this.count += 1;
        return true;
    }
    
    var arr = [ 1, 2, 3, 4 ];
    
    var context = {
        'sum': 0,
        'count': 0
    };
    
    var bool = everyBy( arr, sum, context );
    // returns true
    
    var mean = context.sum / context.count;
    // returns 2.5

    Notes

    • A collection may be either an Array, Typed Array, or an array-like Object (excluding strings and functions).

    • If provided an empty collection, the function returns true.

      function untrue() {
          return false;
      }
      var bool = everyBy( [], untrue );
      // returns true
    • The function differs from Array.prototype.every in the following ways:

      • The function does not skip undefined elements.

        function log( value, index ) {
            console.log( '%s: %s', index, value );
            return true;
        }
        
        var arr = [ 1, , , 4 ];
        
        var bool = everyBy( arr, log );
        /* =>
            0: 1
            1: undefined
            2: undefined
            3: 4
        */
      • The function provides limited support for dynamic collections (i.e., collections whose length changes during execution).

    Examples

    var randu = require( '@stdlib/random-base-randu' );
    var everyBy = require( '@stdlib/utils-every-by' );
    
    function isPositive( value ) {
        return ( value > 0 );
    }
    
    var bool;
    var arr;
    var i;
    
    arr = new Array( 100 );
    for ( i = 0; i < arr.length; i++ ) {
        arr[ i ] = randu();
    }
    
    bool = everyBy( arr, isPositive );
    // 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

    Chat


    License

    See LICENSE.

    Copyright

    Copyright © 2016-2021. The Stdlib Authors.

    Install

    npm i @stdlib/utils-every-by

    Homepage

    stdlib.io

    DownloadsWeekly Downloads

    1

    Version

    0.0.7

    License

    Apache-2.0

    Unpacked Size

    42.3 kB

    Total Files

    9

    Last publish

    Collaborators

    • stdlib-bot
    • kgryte
    • planeshifter
    • rreusser