Node.js

import {ethers} from 'ethers';

function split(s) {
	return s ? s.split('.') : [];
}

export class Node extends Map {
	static root() {
		return new this(null, ethers.ZeroHash, '[root]');
	}
	static create(name) {
		return name instanceof this ? name : this.root().create(name);
	}
	constructor(parent, namehash, label, labelhash) {
		super();
		this.parent = parent;
		this.namehash = namehash;
		this.label = label;
		this.labelhash = labelhash;
	}
	get root() {
		let x = this;
		while (x.parent) x = x.parent;
		return x;
	}
	get name() {
		if (!this.parent) return '';
		let v = [];
		for (let x = this; x.parent; x = x.parent) v.push(x.label);
		return v.join('.');
	}
	get dns() {
		return ethers.getBytes(ethers.dnsEncode(this.name, 255));
	}
	get depth() {
		let n = 0;
		for (let x = this; x.parent; x = x.parent) ++n;
		return n;
	}
	get nodes() {
		let n = 0;
		this.scan(() => ++n);
		return n;
	}
	get isETH2LD() {
		return this.parent?.name === 'eth';
	}
	find(name) {
		return split(name).reduceRight((n, s) => n?.get(s), this);
	}
	create(name) {
		return split(name).reduceRight((n, s) => n.child(s), this);
	}
	unique(prefix = 'u') {
		for (let i = 1; ; i++) {
			let label = prefix + i;
			if (!this.has(label)) return this.child(label);
		}
	}
	child(label) {
		let node = this.get(label);
		if (!node) {
			let labelhash = ethers.id(label)
			let namehash = ethers.solidityPackedKeccak256(['bytes32', 'bytes32'], [this.namehash, labelhash]);
			node = new this.constructor(this, namehash, label, labelhash);
			this.set(label, node);
		}
		return node;
	}
	scan(fn, level = 0) {
		fn(this, level++);
		for (let x of this.values()) {
			x.scan(fn, level);
		}
	}
	flat() {
		let v = [];
		this.scan(x => v.push(x));
		return v;
	}
	print(format = x => x.label) {
		this.scan((x, n) => console.log('  '.repeat(n) + format(x)));
	}
	toString() {
		return this.name;
	}
}