Graph with Reflexivity

A lightweight JavaScript implementation of a directed graph where every node automatically has a self‑loop (reflexive edge).
The library is intentionally minimal and does not depend on any external graph libraries or Python code.

Features

Automatic reflexivity – when a node is added, an edge from the node to itself is created.
Directed edges – you can add edges in any direction.
Simple API – add nodes, add edges, query edges, list nodes, list edges.
Pure JavaScript – works in Node.js environments.

Installation

npm install graph-reflexivity

If you want to run the tests or develop locally, clone the repository and run npm install.

Usage

const Graph = require('graph-reflexivity');

const g = new Graph();

// Add nodes
g.addNode('A');
g.addNode('B');

// Add directed edge A → B
g.addEdge('A', 'B');

// Reflexive edges are automatically added
console.log(g.hasEdge('A', 'A')); // true
console.log(g.hasEdge('B', 'B')); // true

// Query
console.log(g.getNeighbors('A')); // ['A', 'B']
console.log(g.nodes());          // ['A', 'B']
console.log(g.edges());          // [['A', 'A'], ['B', 'B'], ['A', 'B']]

API

Method	Description
`addNode(node)`	Adds a node and its reflexive edge.
`addEdge(from, to)`	Adds a directed edge; missing nodes are created automatically.
`hasEdge(from, to)`	Returns `true` if an edge exists.
`getNeighbors(node)`	Returns an array of all neighbors of `node`.
`nodes()`	Returns an array of all nodes.
`edges()`	Returns an array of `[from, to]` pairs for all edges.

Testing

The project uses Jest for unit tests.

npm test

All tests are located in the tests/ directory.

License

Feel free to open issues or pull requests if you find bugs or want to add features.

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