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• About
• Status
• Related packages
• Installation
• Dependencies
• API
• Basic usage example
• Authors
• License

About

Bi-directional index mapping arbitrary keys to numeric IDs & vice versa.

This package contains functionality which was previously part of and has been extracted from the @thi.ng/associative package.

Status

STABLE - used in production

Search or submit any issues for this package

Related packages

• @thi.ng/associative - ES Map/Set-compatible implementations with customizable equality semantics & supporting operations

Installation

yarn add @thi.ng/bidir-index

ESM import:

import * as bi from "@thi.ng/bidir-index";

Browser ESM import:

<script type="module" src="https://esm.run/@thi.ng/bidir-index"></script>

JSDelivr documentation

For Node.js REPL:

const bi = await import("@thi.ng/bidir-index");

Package sizes (brotli'd, pre-treeshake): ESM: 1.04 KB

Dependencies

• @thi.ng/api
• @thi.ng/checks

Note: @thi.ng/api is in most cases a type-only import (not used at runtime)

API

Generated API docs

TODO

Basic usage example

import { defBidirIndex, encodeObject, decodeObject } from "@thi.ng/bidir-index";

const index = defBidirIndex<string>();

// given object keys are auto-indexed, array initialized with given default
console.log(
  encodeObject(index, { r: 1, g: 2, b: 3, a: 4 }, 0)
);
// [1, 2, 3, 4]

// use custom default and without updating index
console.log(
  encodeObject(index, { b: 3, r: 1, g: 2 }, -1, false)
);
// [1, 2, 3, -1] (missing key `a` mapped to given default value)

// decode with defaults/fallback
console.log(
  decodeObject(index, [255, 128, 64], { a: 1 })
);
// { r: 255, g: 128, b: 64, a: 1 }

// add more keys to index (already known ones will be skipped)
// returns array of mapped IDs for given keys
index.addAll(["r", "g", "b", "a", "foo"]);
// [0, 1, 2, 3, 4]

// decoding will skip nullish values
console.log(
  decodeObject(index, [null, null, null, null, "bar"])
);
// { foo: "bar" }

Authors

• Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-bidir-index,
  title = "@thi.ng/bidir-index",
  author = "Karsten Schmidt",
  note = "https://thi.ng/bidir-index",
  year = 2022
}

License

© 2022 - 2026 Karsten Schmidt // Apache License 2.0