#  [](https://www.npmjs.com/package/@thi.ng/zipper)  [](https://mastodon.thi.ng/@toxi) > [!NOTE] > This is one of 205 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) - [Related packages](#related-packages) - [Blog posts](#blog-posts) - [Installation](#installation) - [Dependencies](#dependencies) - [API](#api) - [Benchmark](#benchmark) - [Authors](#authors) - [License](#license) ## About Functional tree editing, manipulation & navigation. Immutable, semi-functional, structural tree editing, manipulation & navigation, based on my fork and optimizations to [fast-zip](https://github.com/postspectacular/fast-zip), which in turn is based on [clojure.zip](https://clojure.github.io/clojure/clojure.zip-api.html) and which itself is based on the original data structure invented by Gérard Huet in 1997. Reference: https://en.wikipedia.org/wiki/Zipper_(data_structure) ## Status **STABLE** - used in production [Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Bzipper%5D+in%3Atitle) ## Related packages - [@thi.ng/gp](https://github.com/thi-ng/umbrella/tree/develop/packages/gp) - Genetic programming helpers & strategies (tree based & multi-expression programming) ### Blog posts - [Evolutionary failures (Part 1)](https://medium.com/@thi.ng/evolutionary-failures-part-1-54522c69be37) ## Installation ```bash yarn add @thi.ng/zipper ``` ESM import: ```ts import * as zip from "@thi.ng/zipper"; ``` Browser ESM import: ```html ``` [JSDelivr documentation](https://www.jsdelivr.com/) For Node.js REPL: ```js const zip = await import("@thi.ng/zipper"); ``` Package sizes (brotli'd, pre-treeshake): ESM: 1.02 KB ## Dependencies - [@thi.ng/api](https://github.com/thi-ng/umbrella/tree/develop/packages/api) - [@thi.ng/arrays](https://github.com/thi-ng/umbrella/tree/develop/packages/arrays) - [@thi.ng/checks](https://github.com/thi-ng/umbrella/tree/develop/packages/checks) - [@thi.ng/errors](https://github.com/thi-ng/umbrella/tree/develop/packages/errors) Note: @thi.ng/api is in _most_ cases a type-only import (not used at runtime) ## API [Generated API docs](https://docs.thi.ng/umbrella/zipper/) ```ts import { arrayZipper } from "@thi.ng/zipper"; const x = [1, [5, 4, 3, 2], 6]; // create zipper for given array const a = arrayZipper(x); // .next navigates to logically next location (depth-first) // .node retrieves a location's value a.next.node // 1 a.next.next.node // [5, 4, 3, 2] // all navigation verbs: // prev, left, right, up, down, leftmost, rightmost a.next.next.down.rightmost.node // 2 // navigate to value `3`, remove it // then append `7` at top level // and apply changes by requesting root value // (the latter is the actual zip operation) a.next.next.down.rightmost.left.remove().up.up.appendChild(7).root // [ 1, [ 5, 4, 2 ], 6, 7 ] // the same edits in different order a.appendChild(7).next.next.down.rightmost.left.remove().root // [ 1, [ 5, 4, 2 ], 6, 7 ] // insert child at the front a.next.next.insertChild(10).root // [ 1, [ 10, 5, 4, 3, 2 ], 6 ] // replace the nested array a.next.next.replace(10).root // [1, 10, 6] // all editing is immutable, original is untouched... x // [ 1, [ 5, 4, 3, 2 ], 6 ] ``` ## Benchmark For better comparison, the included benchmarks are also ported from the [fast-zip](https://github.com/postspectacular/fast-zip) package and measure traversal & editing of a tree of 10 x 10 x 10 values. Measurements for MBP 2015 2.8GHz, 16GB, node v12.10.0: ```text $ node bench/index.js walk: warmup... 2562ms warmup... 2469ms warmup... 2460ms total: 2476ms, mean: 0.2476ms, runs: 10000 edit: warmup... 4660ms warmup... 4573ms warmup... 4566ms total: 4616ms, mean: 0.4616ms, runs: 10000 ``` ## Authors - [Karsten Schmidt](https://thi.ng) If this project contributes to an academic publication, please cite it as: ```bibtex @misc{thing-zipper, title = "@thi.ng/zipper", author = "Karsten Schmidt", note = "https://thi.ng/zipper", year = 2015 } ``` ## License © 2015 - 2025 Karsten Schmidt // Apache License 2.0