@stdlib/array-to-iterator

<details> <summary> About stdlib... </summary> <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p> <p>The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.</p> <p>When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.</p> <p>To join us in bringing numerical computing to the web, get started by checking us out on <a href="https://github.com/stdlib-js/stdlib">GitHub</a>, and please consider <a href="https://opencollective.com/stdlib">financially supporting stdlib</a>. We greatly appreciate your continued support!</p> </details> # array2iterator [![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]  > Create an iterator from an array-like object.  <section class="intro"> </section>   <section class="installation"> ## Installation ```bash npm install @stdlib/array-to-iterator ``` </section> <section class="usage"> ## Usage ```javascript var array2iterator = require( '@stdlib/array-to-iterator' ); ``` #### array2iterator( src\[, mapFcn\[, thisArg]] ) Returns an iterator which iterates over each element in an array-like `object`. ```javascript var it = array2iterator( [ 1, 2, 3, 4 ] ); // returns <Object> var v = it.next().value; // returns 1 v = it.next().value; // returns 2 v = it.next().value; // returns 3 // ... ``` The returned iterator protocol-compliant object has the following properties: - **next**: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a `value` property and a `done` property having a `boolean` value indicating whether the iterator is finished. - **return**: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object. To invoke a function for each `src` value, provide a callback function. ```javascript function fcn( v ) { return v * 10.0; } var it = array2iterator( [ 1, 2, 3, 4 ], fcn ); // returns <Object> var v = it.next().value; // returns 10.0 v = it.next().value; // returns 20.0 v = it.next().value; // returns 30.0 // ... ``` The invoked function is provided three arguments: - **value**: iterated value. - **index**: iterated value index. - **src**: source array-like object. ```javascript function fcn( v, i ) { return v * (i+1); } var it = array2iterator( [ 1, 2, 3, 4 ], fcn ); // returns <Object> var v = it.next().value; // returns 1 v = it.next().value; // returns 4 v = it.next().value; // returns 9 // ... ``` To set the callback function execution context, provide a `thisArg`. ```javascript function fcn( v ) { this.count += 1; return v * 10.0; } var ctx = { 'count': 0 }; var it = array2iterator( [ 1, 2, 3, 4 ], fcn, ctx ); // returns <Object> var v = it.next().value; // returns 10.0 v = it.next().value; // returns 20.0 v = it.next().value; // returns 30.0 var count = ctx.count; // returns 3 ``` </section>   <section class="notes"> ## Notes - If an environment supports `Symbol.iterator`, the returned iterator is iterable. - If provided a generic `array`, the returned iterator does **not** ignore holes. To achieve greater performance for sparse arrays, use [`@stdlib/array-to-sparse-iterator`][@stdlib/array/to-sparse-iterator]. - A returned iterator does **not** copy a provided array-like `object`. To ensure iterable reproducibility, copy a provided array-like `object` **before** creating an iterator. Otherwise, any changes to the contents of an array-like `object` will be reflected in the returned iterator. - In environments supporting `Symbol.iterator`, the function **explicitly** does **not** invoke an array's `@@iterator` method, regardless of whether this method is defined. To convert an array to an implementation defined iterator, invoke this method directly. - The returned iterator supports array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array-complex64`][@stdlib/array/complex64]). </section>   <section class="examples"> ## Examples  ```javascript var Float64Array = require( '@stdlib/array-float64' ); var inmap = require( '@stdlib/utils-inmap' ); var randu = require( '@stdlib/random-base-randu' ); var array2iterator = require( '@stdlib/array-to-iterator' ); function scale( v, i ) { return v * (i+1); } // Create an array filled with random numbers: var arr = inmap( new Float64Array( 100 ), randu ); // Create an iterator from the array which scales iterated values: var it = array2iterator( arr, scale ); // Perform manual iteration... var v; while ( true ) { v = it.next(); if ( v.done ) { break; } console.log( v.value ); } ``` </section>   <section class="references"> </section>   <section class="related"> * * * ## See Also - <span class="package-name">[`@stdlib/array-from-iterator`][@stdlib/array/from-iterator]</span><span class="delimiter">: </span><span class="description">create (or fill) an array from an iterator.</span> - <span class="package-name">[`@stdlib/array-to-circular-iterator`][@stdlib/array/to-circular-iterator]</span><span class="delimiter">: </span><span class="description">create an iterator which repeatedly iterates over the elements of an array-like object.</span> - <span class="package-name">[`@stdlib/array-to-iterator-right`][@stdlib/array/to-iterator-right]</span><span class="delimiter">: </span><span class="description">create an iterator from an array-like object, iterating from right to left.</span> - <span class="package-name">[`@stdlib/array-to-strided-iterator`][@stdlib/array/to-strided-iterator]</span><span class="delimiter">: </span><span class="description">create an iterator from a strided array-like object.</span> </section>   <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 © 2016-2024. The Stdlib [Authors][stdlib-authors]. </section>   <section class="links"> [npm-image]: http://img.shields.io/npm/v/@stdlib/array-to-iterator.svg [npm-url]: https://npmjs.org/package/@stdlib/array-to-iterator [test-image]: https://github.com/stdlib-js/array-to-iterator/actions/workflows/test.yml/badge.svg?branch=v0.2.2 [test-url]: https://github.com/stdlib-js/array-to-iterator/actions/workflows/test.yml?query=branch:v0.2.2 [coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/array-to-iterator/main.svg [coverage-url]: https://codecov.io/github/stdlib-js/array-to-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-to-iterator/tree/deno [deno-readme]: https://github.com/stdlib-js/array-to-iterator/blob/deno/README.md [umd-url]: https://github.com/stdlib-js/array-to-iterator/tree/umd [umd-readme]: https://github.com/stdlib-js/array-to-iterator/blob/umd/README.md [esm-url]: https://github.com/stdlib-js/array-to-iterator/tree/esm [esm-readme]: https://github.com/stdlib-js/array-to-iterator/blob/esm/README.md [branches-url]: https://github.com/stdlib-js/array-to-iterator/blob/main/branches.md [stdlib-license]: https://raw.githubusercontent.com/stdlib-js/array-to-iterator/main/LICENSE [@stdlib/array/to-sparse-iterator]: https://www.npmjs.com/package/@stdlib/array-to-sparse-iterator [@stdlib/array/complex64]: https://www.npmjs.com/package/@stdlib/array-complex64  [@stdlib/array/from-iterator]: https://www.npmjs.com/package/@stdlib/array-from-iterator [@stdlib/array/to-circular-iterator]: https://www.npmjs.com/package/@stdlib/array-to-circular-iterator [@stdlib/array/to-iterator-right]: https://www.npmjs.com/package/@stdlib/array-to-iterator-right [@stdlib/array/to-strided-iterator]: https://www.npmjs.com/package/@stdlib/array-to-strided-iterator  </section>