todo-app.ts ts 

import {
	type Component,
	type SignalProducer,
	component,
	first,
	on,
	selection,
	setAttribute,
	setProperty,
	setText,
} from "../../../";
import type { InputButtonProps } from "../input-button/input-button";
import type { InputCheckboxProps } from "../input-checkbox/input-checkbox";
import type { InputFieldProps } from "../input-field/input-field";
import type { InputRadiogroupProps } from "../input-radiogroup/input-radiogroup";

export type TodoAppProps = {
	active: Component<InputCheckboxProps>[];
	completed: Component<InputCheckboxProps>[];
};

export default component(
	"todo-app",
	{
		active: ((el) =>
			selection<Component<InputCheckboxProps>>(
				el,
				"input-checkbox:not([checked])",
			)) as SignalProducer<HTMLElement, Component<InputCheckboxProps>[]>,
		completed: ((el) =>
			selection<Component<InputCheckboxProps>>(
				el,
				"input-checkbox[checked]",
			)) as SignalProducer<HTMLElement, Component<InputCheckboxProps>[]>,
	},
	(el) => {
		const input =
			el.querySelector<Component<InputFieldProps>>("input-field");
		if (!input) throw new Error("No input field found");
		const template = el.querySelector("template");
		if (!template) throw new Error("No template found");
		const list = el.querySelector("ol");
		if (!list) throw new Error("No list found");

		return [
			// Control todo input form
			first<TodoAppProps, Component<InputButtonProps>>(
				".submit",
				setProperty("disabled", () => !input.length),
			),
			first(
				"form",
				on("submit", (e: Event) => {
					e.preventDefault();
					queueMicrotask(() => {
						const value = input.value.toString().trim();
						if (!value) return;
						const li = document.importNode(
							template.content,
							true,
						).firstElementChild;
						if (!(li instanceof HTMLLIElement))
							throw new Error(
								"Invalid template for list item; expected <li>",
							);
						li
							.querySelector("slot")
							?.replaceWith(String(input.value));
						list.append(li);
						input.clear();
					});
				}),
			),

			// Control todo list
			first(
				"ol",
				setAttribute(
					"filter",
					() =>
						el.querySelector<Component<InputRadiogroupProps>>(
							"input-radiogroup",
						)?.value ?? "all",
				),
				on("click", (e: Event) => {
					const target = e.target as HTMLElement;
					if (target.localName === "button")
						target.closest("li")!.remove();
				}),
			),

			// Update count elements
			first(
				".count",
				setText(() => String(el.active.length)),
			),
			first<TodoAppProps, HTMLElement>(
				".singular",
				setProperty("hidden", () => el.active.length > 1),
			),
			first<TodoAppProps, HTMLElement>(
				".plural",
				setProperty("hidden", () => el.active.length === 1),
			),
			first<TodoAppProps, HTMLElement>(
				".remaining",
				setProperty("hidden", () => !el.active.length),
			),
			first<TodoAppProps, HTMLElement>(
				".all-done",
				setProperty("hidden", () => !!el.active.length),
			),

			// Control clear-completed button
			first<TodoAppProps, Component<InputButtonProps>>(
				".clear-completed",
				setProperty("disabled", () => !el.completed.length),
				setProperty("badge", () =>
					el.completed.length > 0 ? String(el.completed.length) : "",
				),
				on("click", () => {
					const items = Array.from(el.querySelectorAll("ol li"));
					for (let i = items.length - 1; i >= 0; i--) {
						const task = items[i].querySelector("input-checkbox");
						if (task?.checked) items[i].remove();
					}
				}),
			),
		];
	},
);