{"id":27432225,"url":"https://github.com/stdlib-js/utils-decorate-after","last_synced_at":"2025-04-14T16:19:01.512Z","repository":{"id":62716159,"uuid":"525953068","full_name":"stdlib-js/utils-decorate-after","owner":"stdlib-js","description":"Decorate a provided function such that the function's return value is provided as an argument to another function.","archived":false,"fork":false,"pushed_at":"2024-12-30T05:06:27.000Z","size":819,"stargazers_count":1,"open_issues_count":0,"forks_count":0,"subscribers_count":3,"default_branch":"main","last_synced_at":"2025-04-12T13:40:12.855Z","etag":null,"topics":["decorate","decorator","fcn","fun","func","function","functional","javascript","node","node-js","nodejs","stdlib","transform","util","utilities","utils"],"latest_commit_sha":null,"homepage":"https://github.com/stdlib-js/stdlib","language":"JavaScript","has_issues":false,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"apache-2.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/stdlib-js.png","metadata":{"files":{"readme":"README.md","changelog":"CHANGELOG.md","contributing":"CONTRIBUTING.md","funding":null,"license":"LICENSE","code_of_conduct":"CODE_OF_CONDUCT.md","threat_model":null,"audit":null,"citation":"CITATION.cff","codeowners":null,"security":"SECURITY.md","support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null,"zenodo":null},"funding":{"github":["stdlib-js"],"open_collective":"stdlib","tidelift":"npm/@stdlib/stdlib"}},"created_at":"2022-08-17T21:03:22.000Z","updated_at":"2024-12-30T03:15:43.000Z","dependencies_parsed_at":"2023-02-17T06:40:32.986Z","dependency_job_id":"92a3712d-f3ac-4853-b1c0-036c46664126","html_url":"https://github.com/stdlib-js/utils-decorate-after","commit_stats":{"total_commits":36,"total_committers":1,"mean_commits":36.0,"dds":0.0,"last_synced_commit":"eff37765d80e0d2ad9e974868e56e7b2a26cf638"},"previous_names":[],"tags_count":20,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-decorate-after","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-decorate-after/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-decorate-after/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/stdlib-js%2Futils-decorate-after/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/stdlib-js","download_url":"https://codeload.github.com/stdlib-js/utils-decorate-after/tar.gz/refs/heads/main","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":248801817,"owners_count":21163728,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["decorate","decorator","fcn","fun","func","function","functional","javascript","node","node-js","nodejs","stdlib","transform","util","utilities","utils"],"created_at":"2025-04-14T16:18:59.308Z","updated_at":"2025-04-14T16:19:01.498Z","avatar_url":"https://github.com/stdlib-js.png","language":"JavaScript","readme":"\u003c!--\n\n@license Apache-2.0\n\nCopyright (c) 2022 The Stdlib Authors.\n\nLicensed under the Apache License, Version 2.0 (the \"License\");\nyou may not use this file except in compliance with the License.\nYou may obtain a copy of the License at\n\n   http://www.apache.org/licenses/LICENSE-2.0\n\nUnless required by applicable law or agreed to in writing, software\ndistributed under the License is distributed on an \"AS IS\" BASIS,\nWITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\nSee the License for the specific language governing permissions and\nlimitations under the License.\n\n--\u003e\n\n\n\u003cdetails\u003e\n  \u003csummary\u003e\n    About stdlib...\n  \u003c/summary\u003e\n  \u003cp\u003eWe 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.\u003c/p\u003e\n  \u003cp\u003eThe 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.\u003c/p\u003e\n  \u003cp\u003eWhen 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.\u003c/p\u003e\n  \u003cp\u003eTo join us in bringing numerical computing to the web, get started by checking us out on \u003ca href=\"https://github.com/stdlib-js/stdlib\"\u003eGitHub\u003c/a\u003e, and please consider \u003ca href=\"https://opencollective.com/stdlib\"\u003efinancially supporting stdlib\u003c/a\u003e. We greatly appreciate your continued support!\u003c/p\u003e\n\u003c/details\u003e\n\n# decorateAfter\n\n[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] \u003c!-- [![dependencies][dependencies-image]][dependencies-url] --\u003e\n\n\u003e Decorate a provided function such that the function's return value is provided as an argument to another function.\n\n\u003c!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --\u003e\n\n\u003csection class=\"intro\"\u003e\n\n\u003c/section\u003e\n\n\u003c!-- /.intro --\u003e\n\n\u003c!-- Package usage documentation. --\u003e\n\n\u003csection class=\"installation\"\u003e\n\n## Installation\n\n```bash\nnpm install @stdlib/utils-decorate-after\n```\n\nAlternatively,\n\n-   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]).\n-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).\n-   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]).\n\nThe [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.\n\nTo 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.\n\n\u003c/section\u003e\n\n\u003csection class=\"usage\"\u003e\n\n## Usage\n\n```javascript\nvar decorateAfter = require( '@stdlib/utils-decorate-after' );\n```\n\n#### decorateAfter( fcn, arity, after\\[, thisArg] )\n\nDecorates a provided function such that the function's return value is provided as an argument to another function.\n\n```javascript\nvar abs = require( '@stdlib/math-base-special-abs' );\n\nfunction negate( v ) {\n    return -v;\n}\n\nvar f = decorateAfter( abs, abs.length, negate );\n// returns \u003cFunction\u003e\n\nvar bool = ( abs.length === f.length );\n// returns true\n\nvar v = f( -5 );\n// returns -5\n\nv = f( 5 );\n// returns -5\n```\n\nDecorators are intended to be transparent, meaning that, when interfacing with an API, the decorated API should have the same signature (i.e., number of parameters) as the decorated function. Thus, a typical value for `arity` is `fcn.length`. This function does not require equality, however, and the `arity` argument is allowed to diverge from that of the decorated function. Specifying a differing `arity` does **not** affect function evaluation behavior, as the returned function passes all provided arguments to the decorated function.\n\n```javascript\nvar abs = require( '@stdlib/math-base-special-abs' );\n\nfunction negate( v ) {\n    return -v;\n}\n\nvar f = decorateAfter( abs, 0, negate );\n// returns \u003cFunction\u003e\n\nvar bool = ( abs.length === f.length );\n// returns false\n\nvar v = f( -5 );\n// returns -5\n\nv = f( 5 );\n// returns -5\n```\n\nTo specify the function execution context for `after`, provide a `thisArg` argument.\n\n\u003c!-- eslint-disable no-invalid-this --\u003e\n\n```javascript\nvar abs = require( '@stdlib/math-base-special-abs' );\n\nfunction counter() {\n    this.count += 1;\n}\n\nvar ctx = {\n    'count': 0\n};\n\nvar f = decorateAfter( abs, abs.length, counter, ctx );\n// returns \u003cFunction\u003e\n\nvar v = f( -5 );\n// returns 5\n\nv = f( 5 );\n// returns 5\n\nvar count = ctx.count;\n// returns 2\n```\n\n#### decorateAfter.factory( fcn, arity, after\\[, thisArg] )\n\nUses code generation to decorate a provided function such that the function's return value is provided as an argument to another function.\n\n```javascript\nvar abs = require( '@stdlib/math-base-special-abs' );\n\nfunction negate( v ) {\n    return -v;\n}\n\nvar f = decorateAfter.factory( abs, abs.length, negate );\n// returns \u003cFunction\u003e\n\nvar bool = ( abs.length === f.length );\n// returns true\n\nvar v = f( -5 );\n// returns -5\n\nv = f( 5 );\n// returns -5\n```\n\nArgument behavior is the same as for `decorateAfter` above.\n\n\u003c/section\u003e\n\n\u003c!-- /.usage --\u003e\n\n\u003c!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --\u003e\n\n\u003csection class=\"notes\"\u003e\n\n## Notes\n\n-   If the `after` function returns `undefined`, the returned decorator returns the return value of the decorated function `fcn`; otherwise, the returned decorator returns the return value of `after`.\n-   Code generation may be problematic in browser contexts enforcing a strict [content security policy][mdn-csp] (CSP). If running in or targeting an environment with a CSP, avoid using code generation.\n-   For non-native functions, the code generation API supports returning a decorator whose API exactly matches the API of the decorated function, including function length and parameter names. For native functions, due to how native functions serialize to strings, the code generation API generates placeholder parameter names, which are unlikely to match the canonical parameter names. Using placeholder parameter names ensures that the length of the decorator (i.e., number of parameters) matches the decorated function and, except in scenarios involving function source code inspection, will not affect runtime behavior.\n-   For the non-code generation API, the returned decorator supports an `arity` less than or equal to `10` (i.e., the maximum arity of the returned function is `10`). For an arity greater than `10`, the returned function has an arity equal to `0`. While this violates strict notions of a decorator, for all practical purposes, this is unlikely to be an issue, as the vast majority of functions have fewer than `10` parameters and the need for explicitly checking function length is relatively uncommon.\n-   The decorators returned by the code generation and non-code generation APIs should have the same performance characteristics, and, thus, neither API should have a performance advantage over the other. The main advantage of the code generation API is the ability to return a decorator whose signature exactly matches the signature of a non-native decorated function.\n-   Common use cases for decorating a function with additional actions **after** invocation include logging, capturing invocation statistics, and validating return values.\n\n\u003c/section\u003e\n\n\u003c!-- /.notes --\u003e\n\n\u003c!-- Package usage examples. --\u003e\n\n\u003csection class=\"examples\"\u003e\n\n## Examples\n\n\u003c!-- eslint no-undef: \"error\" --\u003e\n\n\u003c!-- eslint-disable no-invalid-this --\u003e\n\n```javascript\nvar discreteUniform = require( '@stdlib/random-base-discrete-uniform' );\nvar format = require( '@stdlib/string-format' );\nvar decorateAfter = require( '@stdlib/utils-decorate-after' );\n\nfunction count() {\n    this.count += 1;\n}\n\nfunction greet() {\n    return 'Hello!';\n}\n\nfunction randstr( f ) {\n    var str;\n    var i;\n\n    str = [];\n    for ( i = 0; i \u003c discreteUniform( 1, 10 ); i++ ) {\n        str.push( f() );\n    }\n    return str.join( ' ' );\n}\n\n// Create an evaluation context to allow tracking how many times a function is invoked:\nvar ctx = {\n    'count': 0\n};\n\n// Decorate a function with a counter:\nvar f = decorateAfter( greet, greet.length, count, ctx );\n\n// Generate a random greeting:\nvar str = randstr( f );\n// returns \u003cstring\u003e\n\n// Check how many times the function was invoked:\nvar c = ctx.count;\n// returns \u003cnumber\u003e\n```\n\n\u003c/section\u003e\n\n\u003c!-- /.examples --\u003e\n\n\u003c!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. --\u003e\n\n\u003csection class=\"references\"\u003e\n\n\u003c/section\u003e\n\n\u003c!-- /.references --\u003e\n\n\u003c!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --\u003e\n\n\u003csection class=\"related\"\u003e\n\n\u003c/section\u003e\n\n\u003c!-- /.related --\u003e\n\n\u003c!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --\u003e\n\n\n\u003csection class=\"main-repo\" \u003e\n\n* * *\n\n## Notice\n\nThis 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.\n\nFor 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].\n\n#### Community\n\n[![Chat][chat-image]][chat-url]\n\n---\n\n## License\n\nSee [LICENSE][stdlib-license].\n\n\n## Copyright\n\nCopyright \u0026copy; 2016-2024. The Stdlib [Authors][stdlib-authors].\n\n\u003c/section\u003e\n\n\u003c!-- /.stdlib --\u003e\n\n\u003c!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --\u003e\n\n\u003csection class=\"links\"\u003e\n\n[npm-image]: http://img.shields.io/npm/v/@stdlib/utils-decorate-after.svg\n[npm-url]: https://npmjs.org/package/@stdlib/utils-decorate-after\n\n[test-image]: https://github.com/stdlib-js/utils-decorate-after/actions/workflows/test.yml/badge.svg?branch=main\n[test-url]: https://github.com/stdlib-js/utils-decorate-after/actions/workflows/test.yml?query=branch:main\n\n[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/utils-decorate-after/main.svg\n[coverage-url]: https://codecov.io/github/stdlib-js/utils-decorate-after?branch=main\n\n\u003c!--\n\n[dependencies-image]: https://img.shields.io/david/stdlib-js/utils-decorate-after.svg\n[dependencies-url]: https://david-dm.org/stdlib-js/utils-decorate-after/main\n\n--\u003e\n\n[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg\n[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im\n\n[stdlib]: https://github.com/stdlib-js/stdlib\n\n[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors\n\n[umd]: https://github.com/umdjs/umd\n[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules\n\n[deno-url]: https://github.com/stdlib-js/utils-decorate-after/tree/deno\n[deno-readme]: https://github.com/stdlib-js/utils-decorate-after/blob/deno/README.md\n[umd-url]: https://github.com/stdlib-js/utils-decorate-after/tree/umd\n[umd-readme]: https://github.com/stdlib-js/utils-decorate-after/blob/umd/README.md\n[esm-url]: https://github.com/stdlib-js/utils-decorate-after/tree/esm\n[esm-readme]: https://github.com/stdlib-js/utils-decorate-after/blob/esm/README.md\n[branches-url]: https://github.com/stdlib-js/utils-decorate-after/blob/main/branches.md\n\n[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-decorate-after/main/LICENSE\n\n[mdn-csp]: https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP\n\n\u003c!-- \u003crelated-links\u003e --\u003e\n\n\u003c!-- \u003c/related-links\u003e --\u003e\n\n\u003c/section\u003e\n\n\u003c!-- /.links --\u003e\n","funding_links":["https://github.com/sponsors/stdlib-js","https://opencollective.com/stdlib","https://tidelift.com/funding/github/npm/@stdlib/stdlib"],"categories":[],"sub_categories":[],"project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fstdlib-js%2Futils-decorate-after","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fstdlib-js%2Futils-decorate-after","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fstdlib-js%2Futils-decorate-after/lists"}