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https://github.com/stdlib-js/utils-inmap
Invoke a function for each element in a collection and update the collection in-place.
https://github.com/stdlib-js/utils-inmap
array array-like collection in-place inmap iterate javascript map mutate node node-js nodejs stdlib typed typed-array util utilities utility utils
Last synced: 25 days ago
JSON representation
Invoke a function for each element in a collection and update the collection in-place.
- Host: GitHub
- URL: https://github.com/stdlib-js/utils-inmap
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-14T13:34:48.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2024-12-01T08:21:35.000Z (about 1 month ago)
- Last Synced: 2024-12-10T03:34:27.850Z (25 days ago)
- Topics: array, array-like, collection, in-place, inmap, iterate, javascript, map, mutate, node, node-js, nodejs, stdlib, typed, typed-array, util, utilities, utility, utils
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 872 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
Awesome Lists containing this project
README
About stdlib...
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.
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.
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.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
# inmap
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Invoke a function for each element in a collection and update the collection in-place.
## Installation
```bash
npm install @stdlib/utils-inmap
```
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 inmap = require( '@stdlib/utils-inmap' );
```
#### inmap( collection, fcn\[, thisArg ] )
Invokes a `function` for each element in a `collection` and updates the `collection` in-place.
```javascript
function scale( value, index ) {
return value * index;
}
var arr = [ 1, 2, 3, 4 ];
var out = inmap( arr, scale );
// returns [ 0, 2, 6, 12 ]
var bool = ( out === arr );
// returns true
```
The invoked `function` is provided three arguments:
- **value**: collection element.
- **index**: collection index.
- **collection**: input collection.
Basic support for dynamic collections is provided. Note, however, that index incrementation is monotonically increasing.
```javascript
function scale1( value, index, collection ) {
if ( index === collection.length-1 && collection.length < 10 ) {
collection.push( index+2 );
}
return value * index;
}
var arr = [ 1, 2, 3, 4 ];
var out = inmap( arr, scale1 );
// returns [ 0, 2, 6, 12, 20, 30, 42, 56, 72, 90 ]
function scale2( value, index, collection ) {
collection.shift();
return value * index;
}
arr = [ 1, 2, 3, 4 ];
out = inmap( arr, scale2 );
// returns [ 3, 3 ]
```
To set the function execution context, provide a `thisArg`.
```javascript
function sum( value ) {
this.sum += value;
this.count += 1;
return value;
}
var arr = [ 1, 2, 3, 4 ];
var context = {
'sum': 0,
'count': 0
};
var out = inmap( arr, sum, context );
// returns [ 1, 2, 3, 4 ]
var mean = context.sum / context.count;
// returns 2.5
```
## Notes
- A `collection` may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (excluding `strings` and `functions`).
- The function differs from [`Array.prototype.map`][mdn-array-map] in the following ways:
- The function returns the input `collection`.
- The function modifies `collection` elements in-place.
- The function does **not** skip `undefined` elements.
```javascript
function log( value, index ) {
console.log( '%s: %s', index, value );
return value;
}
var arr = [ 1, , , 4 ];
var out = inmap( arr, log );
/* =>
0: 1
1: undefined
2: undefined
3: 4
*/
```
- The function provides limited support for dynamic collections (i.e., collections whose `length` changes during execution).
## Examples
```javascript
var isEven = require( '@stdlib/assert-is-even' ).isPrimitive;
var inmap = require( '@stdlib/utils-inmap' );
var bool;
var arr;
var out;
var i;
function scale( value, index, collection ) {
if ( isEven( index ) ) {
collection.shift();
} else {
collection.push( index+1 );
}
return value * index;
}
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
arr[ i ] = i;
}
out = inmap( arr, scale );
bool = ( out === arr );
console.log( bool );
console.log( out );
```
* * *
## See Also
- [`@stdlib/utils-for-each`][@stdlib/utils/for-each]: invoke a function for each element in a collection.
- [`@stdlib/utils-inmap-right`][@stdlib/utils/inmap-right]: invoke a function for each element in a collection and update the collection in-place, iterating from right to left.
- [`@stdlib/utils-map`][@stdlib/utils/map]: apply a function to each element in an array and assign the result to an element in an output array.
* * *
## 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].
[npm-image]: http://img.shields.io/npm/v/@stdlib/utils-inmap.svg
[npm-url]: https://npmjs.org/package/@stdlib/utils-inmap
[test-image]: https://github.com/stdlib-js/utils-inmap/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/utils-inmap/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/utils-inmap/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/utils-inmap?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/utils-inmap/tree/deno
[deno-readme]: https://github.com/stdlib-js/utils-inmap/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/utils-inmap/tree/umd
[umd-readme]: https://github.com/stdlib-js/utils-inmap/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/utils-inmap/tree/esm
[esm-readme]: https://github.com/stdlib-js/utils-inmap/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/utils-inmap/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-inmap/main/LICENSE
[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
[mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
[mdn-array-map]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map
[@stdlib/utils/for-each]: https://github.com/stdlib-js/utils-for-each
[@stdlib/utils/inmap-right]: https://github.com/stdlib-js/utils-inmap-right
[@stdlib/utils/map]: https://github.com/stdlib-js/utils-map