npm package: @stdlib/iter-length
Description: Return an iterator's length.
Author: The Stdlib Authors
Latest version: 0.2.3

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    About stdlib...
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# iterLength

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

> Return an [iterator][mdn-iterator-protocol]'s length.

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<section class="intro">

</section>

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<section class="installation">

## Installation

```bash
npm install @stdlib/iter-length
```

</section>

<section class="usage">

## Usage

```javascript
var iterLength = require( '@stdlib/iter-length' );
```

#### iterLength( iterator )

Consumes an entire [iterator][mdn-iterator-protocol] and returns the number of [iterated][mdn-iterator-protocol] values (i.e., the [iterator][mdn-iterator-protocol] length).

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

var arr = array2iterator( [ 0, 0, 0, 0, 1 ] );

var len = iterLength( arr );
// returns 5
```

If a provided [`iterator`][mdn-iterator-protocol] does not return any [iterated][mdn-iterator-protocol] values, the function returns `0`.

```javascript
var iterEmpty = require( '@stdlib/iter-empty' );

var len = iterLength( iterEmpty() );
// returns 0
```

</section>

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<section class="notes">

</section>

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<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random-iter-randu' );
var iterLength = require( '@stdlib/iter-length' );

// Create an iterator which generates uniformly distributed pseudorandom numbers:
var opts = {
    'iter': 100
};
var iter = randu( opts );

// Determine the iterator length:
var len = iterLength( iter );
// returns 100
```

</section>

<!-- /.examples -->

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* * *

## See Also

-   <span class="package-name">[`@stdlib/iter-counter`][@stdlib/iter/counter]</span><span class="delimiter">: </span><span class="description">create an iterator which iteratively returns the number of iterated values.</span>

</section>

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<section class="main-repo" >

* * *

## 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 &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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[npm-image]: http://img.shields.io/npm/v/@stdlib/iter-length.svg
[npm-url]: https://npmjs.org/package/@stdlib/iter-length

[test-image]: https://github.com/stdlib-js/iter-length/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/iter-length/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/iter-length/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/iter-length?branch=main

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[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/iter-length/tree/deno
[deno-readme]: https://github.com/stdlib-js/iter-length/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/iter-length/tree/umd
[umd-readme]: https://github.com/stdlib-js/iter-length/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/iter-length/tree/esm
[esm-readme]: https://github.com/stdlib-js/iter-length/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/iter-length/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/iter-length/main/LICENSE

[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol

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[@stdlib/iter/counter]: https://www.npmjs.com/package/@stdlib/iter-counter

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</section>

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