#  [](https://www.npmjs.com/package/@thi.ng/equiv)  [](https://mastodon.thi.ng/@toxi) > [!NOTE] > This is one of 214 standalone projects, maintained as part > of the [@thi.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo > and anti-framework. > > 🚀 Please help me to work full-time on these projects by [sponsoring me on > GitHub](https://github.com/sponsors/postspectacular). Thank you! ❤️ - [About](#about) - [Status](#status) - [Installation](#installation) - [Dependencies](#dependencies) - [API](#api) - [Implement IEquiv interface](#implement-iequiv-interface) - [Authors](#authors) - [License](#license) ## About Extensible deep value equivalence checking for any data types. Supports: - JS primitives - Arrays - Plain objects - ES6 Sets / Maps - Date - RegExp - Types with [IEquiv](https://github.com/thi-ng/umbrella/tree/develop/packages/api/src/api/equiv.ts) implementation ## Status **STABLE** - used in production [Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Bequiv%5D+in%3Atitle) ## Installation ```bash yarn add @thi.ng/equiv ``` ESM import: ```ts import * as equiv from "@thi.ng/equiv"; ``` Browser ESM import: ```html ``` [JSDelivr documentation](https://www.jsdelivr.com/) For Node.js REPL: ```js const equiv = await import("@thi.ng/equiv"); ``` Package sizes (brotli'd, pre-treeshake): ESM: 436 bytes ## Dependencies None ## API [Generated API docs](https://docs.thi.ng/umbrella/equiv/) ```ts import { equiv } from "@thi.ng/equiv"; equiv( { a: { b: [1, 2] } }, { a: { b: [1, 2] } } ); // true ``` ### Implement IEquiv interface This is useful & required for custom types to take part in `equiv` checks, by default only plain objects & array are traversed deeply. Furthermore, by implementing this interface we can better control which internal values / criteria are required to establish equivalence. In this example we exclude the `meta` property and only check for same type & `children` equality. ```ts import { IEquiv } from "@thi.ng/api"; import { equiv } from "@thi.ng/equiv"; class Node implements IEquiv { meta: any; children: any[]; constructor(children: any[], meta?: any) { this.children = children; this.meta = meta; } equiv(o: any) { return o instanceof Node && equiv(this.children, o.children); } } equiv(new Node([1,2,3], "foo"), new Node([1,2,3], "bar")); // true ``` ## Authors - [Karsten Schmidt](https://thi.ng) If this project contributes to an academic publication, please cite it as: ```bibtex @misc{thing-equiv, title = "@thi.ng/equiv", author = "Karsten Schmidt", note = "https://thi.ng/equiv", year = 2016 } ``` ## License © 2016 - 2026 Karsten Schmidt // Apache License 2.0