@stdlib/utils/mask-arguments/README.md

Standard utilities.

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# maskArguments

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

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## Usage

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

#### maskArguments( fcn, mask\[, thisArg] )

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

```javascript
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`.

<!-- eslint-disable no-restricted-syntax -->

```javascript
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 ]
```

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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

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## Notes

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

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## Examples

<!-- eslint no-undef: "error" -->

```javascript
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;
}
```

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* * *

## See Also

-   <span class="package-name">[`@stdlib/utils/filter-arguments`][@stdlib/utils/filter-arguments]</span><span class="delimiter">: </span><span class="description">create a function that invokes a provided function according to a predicate function.</span>
-   <span class="package-name">[`@stdlib/utils/reject-arguments`][@stdlib/utils/reject-arguments]</span><span class="delimiter">: </span><span class="description">create a function that invokes a provided function according to a predicate function.</span>
-   <span class="package-name">[`@stdlib/utils/reorder-arguments`][@stdlib/utils/reorder-arguments]</span><span class="delimiter">: </span><span class="description">create a function that invokes a provided function with reordered arguments.</span>
-   <span class="package-name">[`@stdlib/utils/reverse-arguments`][@stdlib/utils/reverse-arguments]</span><span class="delimiter">: </span><span class="description">create a function that invokes a provided function with arguments in reverse order.</span>

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[@stdlib/utils/filter-arguments]: https://github.com/stdlib-js/utils/tree/main/filter-arguments

[@stdlib/utils/reject-arguments]: https://github.com/stdlib-js/utils/tree/main/reject-arguments

[@stdlib/utils/reorder-arguments]: https://github.com/stdlib-js/utils/tree/main/reorder-arguments

[@stdlib/utils/reverse-arguments]: https://github.com/stdlib-js/utils/tree/main/reverse-arguments

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