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https://github.com/stdlib-js/array-from-iterator

Create (or fill) an array from an iterator.
https://github.com/stdlib-js/array-from-iterator

arr array convert iter iterate iteration iterator javascript node node-js nodejs stdlib to typed typed-array util utilities utility utils

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Create (or fill) an array from an iterator.

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README 

        



  

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# iterator2array



[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] 



> Create (or fill) an array from an iterator.



## Installation



```bash

npm install @stdlib/array-from-iterator

```



Alternatively,



-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).

-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).

-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).



The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.



To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.



## Usage



```javascript

var iterator2array = require( '@stdlib/array-from-iterator' );

```



#### iterator2array( iterator\[, out]\[, mapFcn\[, thisArg]] )



Creates (or fills) an array from an `iterator`.



```javascript

var randu = require( '@stdlib/random-iter-randu' );



var opts = {

    'iter': 10

};



var arr = iterator2array( randu( opts ) );

// returns 

```



By default, the function creates and fills a generic `array`. To fill an array-like `object`, provide an `out` argument.



```javascript

var Float64Array = require( '@stdlib/array-float64' );

var randu = require( '@stdlib/random-iter-randu' );



var out = new Float64Array( 10 );



var arr = iterator2array( randu(), out );

// returns 



var bool = ( out === arr );

// returns true

```



To invoke a function for each iterated value, provide a callback function.



```javascript

var array2iterator = require( '@stdlib/array-to-iterator' );



function fcn( v ) {

    return v * 10.0;

}



var arr = iterator2array( array2iterator( [ 1, 2, 3, 4 ] ), fcn );

// returns [ 10.0, 20.0, 30.0, 40.0 ]

```



The invoked function is provided two arguments:



-   **value**: iterated value.

-   **index**: iterated value index.



```javascript

var Float64Array = require( '@stdlib/array-float64' );

var randu = require( '@stdlib/random-iter-randu' );



function fcn( v, i ) {

    return v * (i+1);

}



var arr = iterator2array( randu(), new Float64Array( 10 ), fcn );

// returns 

```



To set the callback function execution context, provide a `thisArg`.



```javascript

var Float64Array = require( '@stdlib/array-float64' );

var randu = require( '@stdlib/random-iter-randu' );



function fcn( v ) {

    this.count += 1;

    return v * 10.0;

}



var ctx = {

    'count': 0

};



var arr = iterator2array( randu(), new Float64Array( 10 ), fcn, ctx );

// returns 



var count = ctx.count;

// returns 10

```



## Notes



-   If provided an output array, the function fills the output array with iterated values.

-   Iteration stops when an output array is full **or** an iterator finishes; whichever comes first.

-   By providing an output typed array, one avoids the temporary memory allocation when using the built-in `TypedArray.from`.



## Examples



```javascript

var Float64Array = require( '@stdlib/array-float64' );

var randu = require( '@stdlib/random-iter-randu' );

var iterator2array = require( '@stdlib/array-from-iterator' );



var opts;

var arr;

var it;

var i;



function scale( v, i ) {

    return v * (i+1);

}



// Create an iterator for generating uniformly distributed pseudorandom numbers:

opts = {

    'iter': 10

};

it = randu( opts );



// Fill an array with scaled iterator values:

arr = iterator2array( it, new Float64Array( opts.iter ), scale );



for ( i = 0; i < arr.length; i++ ) {

    console.log( arr[ i ] );

}

```



* * *



## See Also



-   [`@stdlib/array-to-iterator`][@stdlib/array/to-iterator]: create an iterator from an array-like object.

-   [`@stdlib/iter-to-array-view`][@stdlib/iter/to-array-view]: fill an array-like object view with values returned from an iterator.



* * *



## Notice



This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].



#### Community



[![Chat][chat-image]][chat-url]



---



## License



See [LICENSE][stdlib-license].



## Copyright



Copyright © 2016-2025. The Stdlib [Authors][stdlib-authors].



[npm-image]: http://img.shields.io/npm/v/@stdlib/array-from-iterator.svg

[npm-url]: https://npmjs.org/package/@stdlib/array-from-iterator



[test-image]: https://github.com/stdlib-js/array-from-iterator/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/array-from-iterator/actions/workflows/test.yml?query=branch:main



[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/array-from-iterator/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/array-from-iterator?branch=main



[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg

[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im



[stdlib]: https://github.com/stdlib-js/stdlib



[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors



[umd]: https://github.com/umdjs/umd

[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules



[deno-url]: https://github.com/stdlib-js/array-from-iterator/tree/deno

[deno-readme]: https://github.com/stdlib-js/array-from-iterator/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/array-from-iterator/tree/umd

[umd-readme]: https://github.com/stdlib-js/array-from-iterator/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/array-from-iterator/tree/esm

[esm-readme]: https://github.com/stdlib-js/array-from-iterator/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/array-from-iterator/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/array-from-iterator/main/LICENSE



[@stdlib/array/to-iterator]: https://github.com/stdlib-js/array-to-iterator



[@stdlib/iter/to-array-view]: https://github.com/stdlib-js/iter-to-array-view