@stdlib/utils-mask-arguments NPM

maskArguments

Create a function that invokes a provided function according to an argument mask.

Installation

npm install @stdlib/utils-mask-arguments

Usage

var maskArguments = require( '@stdlib/utils-mask-arguments' );

maskArguments( fcn, mask[, thisArg] )

Returns a function that invokes a provided function according to an argument mask.

function foo( a, b ) {
    return [ a, b ];
}

var bar = maskArguments( foo, [ 1, 0, 1 ] );

var out = bar( 1, 2, 3 );
// returns [ 1, 3 ]

To set the this context when invoking the provided function, provide a thisArg.

function Foo() {
    this.x = 1;
    this.y = 2;
}

Foo.prototype.scale = function scale( a, b ) {
    return [ this.x*a, this.y*b ];
};

var ctx = {
    'x': 10,
    'y': 20
};

var foo = new Foo();

var bar = maskArguments( foo.scale, [ 1, 0, 1 ], ctx );

var out = bar( 1, 2, 3 );
// returns [ 10, 60 ]

Notes

Only those arguments having a truthy mask value are applied to a provided function.

Examples

var filledarrayBy = require( '@stdlib/array-filled-by' );
var Uint8Array = require( '@stdlib/array-uint8' );
var add = require( '@stdlib/math-base-ops-add' );
var maskArguments = require( '@stdlib/utils-mask-arguments' );

function fill( i ) {
    return i;
}

// Create a data array:
var x = filledarrayBy( 10, 'float64', fill );

// Create a mask array:
var mask = new Uint8Array( x.length );

// "Unmask" the first element:
mask[ 0 ] = 1;

// Compute the sum of consecutive elements...
var f;
var i;
for ( i = 1; i < x.length; i++ ) {
    // "Unmask" the next element:
    mask[ i ] = 1;

    // Compute the sum:
    f = maskArguments( add, mask );
    console.log( 'sum(x_%d, x_%d) = %d', i-1, i, f.apply( null, x ) );

    // Update the mask:
    mask[ i-1 ] = 0;
}

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.