Tiny baby MVVM with nestable Views

tinyMVVM.js

// Ultra basic DataStore with publisher/subscriber model
function DataStore(state = null) {
	this.state = {};
	if (state !== null) this.state = state;
	this.subscribers = [];
}
DataStore.prototype.stateChanged = function () {
	for (const callback of this.subscribers) callback(() => this.getState());
};
DataStore.prototype.setState = function (newState) {
		this.state = newState;
		this.stateChanged();
};
DataStore.prototype.getState = function () {
	return this.state;
};
DataStore.prototype.subscribe = function (callback) {
	this.subscribers.push(callback);
};
DataStore.prototype.addAction = function (name, callback) {
	this[name] = (...args) => {
		const newState = callback(this.state, ...args);
		if ((typeof newState) === "undefined") return;
		this.setState(newState);
	};
	this[name].bind(this);
};
function View(renderer = null) {
	this.renderer = renderer;
	this.state = {};
	this.oldState = {};
	this.children = {};
	this.childCount = 0;
}
View.prototype.shouldRender = function () {
	return true;
};
View.prototype.render = function (state = null) {
	if (state === null) state = this.state;
	if (!this.shouldRender(state)) return;
	if (this.renderer !== null) this.renderer(state, this.oldState);
	if (this.childCount === 0) return;
	for (const child of Object.values(this.children)) child.setState(state);
};
View.prototype.setState = function (state, render = true) {
	this.oldState = this.state;
	this.state = state;
	if (render) this.render();
};
View.prototype.watch = function (dataStore) {
	dataStore.subscribe(getState => this.setState(getState()));
};
View.prototype.addChild = function (label, renderer = null) {
	this.childCount++;
	if ((typeof label) !== "string") label = this.childCount.toString();
	const child = renderer instanceof View ? renderer : new View(renderer);
	this.children[label] = child;
	return child;
};
View.prototype.removeChild = function (child) {
	if ((typeof child) !== "object") {
		if (child in this.children) {
			delete this.children[child];
			return;
		}
	}
	if (!(child instanceof View)) return;
	for (const label of this.children) {
		if (this.children[label] === child) {
			delete this.children[label];
		}
	}
};

/* EXAMPLE - Logs "bar" to the console:
// Create a DataStore with some initial state:
const datastore = new DataStore({foo: null});
// Create a new top-level View (AKA "Glue View") without a renderer:
const topView = new View();
// Create a new View with a renderer, and add it as a child of the top-level View:
const childView = topView.addChild("Child View", state => console.log(state.foo));
// Subscribe the top-level View to the DataStore, so that it renders when the DataStore state is updated:
topView.watch(datastore);
// Mount the top-level View (Children are mounted too) so that it renders when updated:
topView.mount();
// Set the state of the DataStore, causing the subscribed Views to render:
datastore.setState({foo: "bar"});
*/