UEle

A Reactive frontend library.

yarn: yarn add uele

npm: npm i uele

cdn: https://unpkg.com/uele

module: https://unpkg.com/uele?module

Lite Version

cdn: https://unpkg.com/uele/lite

module: https://unpkg.com/uele/lite?module

import { h, r, is, get, api, props, add, useLive } from "uele/lite";

// @preact/signals, ulive, usignal api config
api.effect = effect;
api.is = (v) => v.peek;
api.get = (v) => v.value;

• Tiny
• Simple API
• Fast
• JSX
• Fragment
• Components
• SVG
• Refs
• Style Maps
• Lazy Components
• Promise
• AsyncIterable
• Control Flow Components - If, For, Show, Switch, Match, Suspense
• Extend with any reactive library using api - effect, is, get
• Efficient Array Diffing with For and map
• Add Any Diffing - Using api.diff
• Automatic Cleanup for Subscriptions
• Extend html attributes and props

1. counter
2. h
3. lazy
4. map
5. Example
6. Utility Functions
   • get
   • r
   • f
   • useLive
7. Props
8. Control Flow Components
   • If and Show
   • For
   • Switch and Match
   • Suspense
9. Cleanup Support
10. Other Settings

• For any other reactive library

11. Thanks and Inspiration
12. License

Counter

Without Build tools

1. h

import { h, useLive } from "uele";

let [count, setCount] = useLive(0);

document.body.append(
  h("main", [
    h("button", { onclick: () => setCount((c) => c - 1) }, "-"),
    count,
    h("button", { onclick: () => setCount((c) => c + 1) }, "+"),
  ])
);

2. html

import { h, useLive } from "uele";
import htm from "htm";
const html = htm.bind(h);

let [count, setCount] = useLive(0);

document.body.append(
  html`
    <main>
      <button onClick=${() => setCount((c) => c - 1)}>-</button>
      ${count}
      <button onClick=${() => setCount((c) => c + 1)}>+</button>
    </main>
  `
);

3. f

import { h, useLive, f } from "uele";
const { button, main } = f(h);

let [count, setCount] = useLive(0);

document.body.append(
  main([
    button({ onclick: () => setCount((c) => c - 1) }, "-"),
    count,
    button({ onclick: () => setCount((c) => c + 1) }, "+"),
  ])
);

With Build tools

4. jsx

import { h, useLive } from "uele";

let [count, setCount] = useLive(0);

document.body.append(
  <main>
    <button onClick={() => setCount((c) => c - 1)}>-</button>
    {count}
    <button onClick={() => setCount((c) => c + 1)}>+</button>
  </main>
);

h

let frag = (
  <>
    {asyncIterable} or {promise} or {any html node or component} or {any reactive signal or library}
  </>
);

lazy

Load a component lazily with an optional fallback

const LazyComp = lazy(() => import("./SomeComp"), <div>Failed</div>);

map

Efficient diffing of an array of items

import { map } from "uele";

let items = o([1, 2, 3]);

const Items = () => {
  return map(
    items,
    (item, i) => (
      <div>
        {item} {i}
      </div>
    ),
    <div>No items</div>
  );
};

Example

import {
  h,
  Fragment,
  lazy,
  api,
  If,
  For,
  map,
  get,
  r,
  useLive,
  props,
} from "uele";

import { o, effect, memo } from "ulive/fn"; // Or any other reactive library

// ulive settings
api.effect = effect;
api.is = (v) => v?.peek;
api.get = (v) => v();

// Check below for other reactive library settings

const LazyComp = lazy(() => import("./lazy"));

// Async Component
const TodoItem = async ({ id }) => {
  let api = await fetch(`https://jsonplaceholder.typicode.com/todos/${id}`);
  let todo = await api.json();

  return (
    <li>
      <span>{todo.title}</span>
      <input type="checkbox" checked={todo.completed} />
    </li>
  );
};

const count = o(0);
const inc = () => count(count() + 1);
const dec = () => count(count() - 1);

const Counter = () => {
  let square = memo(() => count() * count());
  let cube = memo(() => square() * count());
  effect(() => console.log(count(), square(), cube()));
  return (
    <div>
      <div>
        Count: {count} {square} {cube}
      </div>
      <button onclick={inc}>+</button>
      <button onclick={dec}>-</button>
    </div>
  );
};

// AsyncIterator

const asyncIterable = {
  [Symbol.asyncIterator]() {
    return {
      i: 0,
      next() {
        if (this.i < 200)
          return new Promise((ok) =>
            setTimeout(
              () =>
                ok({
                  value: <div>{this.i++}</div>,
                  done: false,
                }),
              10
            )
          );
        return new Promise((ok) => ok({ done: true }));
      },
    };
  },
};

let items = o([1, 2, 3]);

const App = () => (
  <main>
    <Counter />
    <LazyComp />
    <TodoItem />
    {asyncIterable}
    {map(items, (item, i) => (
      <div>
        {item} {i}
      </div>
    ))}
    <svg>...</svg>
  </main>
);

document.body.append(<App />);

Utility Functions

get

A utility function to handle and unwrap values of signals, observables, etc., especially functions.

import { get } from "uele";

let value = get(someReactiveSignal);

r

The r function handles reactive subscriptions, providing a callback when the value changes.

import { r } from "uele";

r(someObservable, (value, is) => {
  console.log("Value changed to", value, is);
});

f

The f function is a utility that provides a convenient shorthand for creating elements using the h function. It returns a proxy that allows you to call HTML elements as functions directly.

import { h, useLive, f } from "uele";
const { button, main } = f(h);

const [count, setCount] = useLive(0);

document.body.append(
  main([
    button({ onclick: () => setCount((c) => c - 1) }, "-"),
    count,
    button({ onclick: () => setCount((c) => c + 1) }, "+"),
  ])
);

useLive

useLive helps manage dynamic parts of the DOM by tracking specific start and end markers.

import { useLive } from "uele";

let [live, setLive] = useLive("....");

let c = 0;
setInterval(() => {
  setLive(c++);
}, 1000);

const App = () => <main>{live}</main>;

Props

The props object allows setting custom properties and event handlers on elements.

import { props } from "uele";

props.set("autofocus", (tag, value, name, attrs) => {
	setTimeout(() => tag.focus(), 0);
});

props.set("validate", (node, validateFn) => {
	node.addEventListener("input", () => {
		const error = validateFn(node.value);
		if (error) {
			console.log("error", error);
		} else {
			console.log("no err");
		}
	});
});

props.set("tooltip", (node, value) => {
	const tooltip = <div class="tooltip">{value}</div>;
	node.addEventListener("mouseenter", () => {
		document.body.appendChild(tooltip);
		const { left, top } = node.getBoundingClientRect();
		tooltip.style.position = "absolute";
		tooltip.style.left = `${left}px`;
		tooltip.style.top = `${top - 20}px`;
	});

	node.addEventListener("mouseleave", () => {
		tooltip.remove();
	});
});

props.set("unmount", (node, cleanupFn) => {
	// Check if the node has a parent node
const setupObserver = () => {
	if (node.parentNode) {
		// Create a MutationObserver to watch for DOM changes (removals)
		const observer = new MutationObserver((mutationsList) => {
			for (let mutation of mutationsList) {
				mutation.removedNodes.forEach((removedNode) => {
					if (removedNode === node) {
						// Node has been removed, trigger the cleanup function
						cleanupFn();
						observer.disconnect(); // Stop observing
					}
				});
			}
		});

		// Start observing the parent node for childList changes (node removals)
		observer.observe(node.parentNode, { childList: true });
	} else {
		// If node has no parentNode, retry after DOM insertion
		requestAnimationFrame(setupObserver); // Try again on the next frame
	}
};

	setupObserver(); // Initialize the observer
});
<input autofocus/>
<input validate={(val) => (val.length < 3 ? "Too short" : "")} />
<button tooltip={{<div>click me!</div>}}>Hover me</button>
<div ref={(v) => { setTimeout(() => v.remove(), 2000)}}
	 unmount={() => console.log("unmounted!")}>
	Remove me
</div>

Control Flow Components

Control flow components accept boolean or reactive values for conditions.

If and Show

import { If, Show } from 'uele';

<If when={cond} fallback={<div>False</div>}>
  <div>True</div>
</If>

<Show when={cond} fallback={<div>False</div>}>
  <div>True</div>
</Show>

For

import { For } from "uele";

<For each={[1, 2, 3]} fallback={<div>No Items</div>}>
  {(val) => <div>{val}</div>}
</For>;

Switch and Match

import { Switch, Match } from "uele";

<Switch fallback={<div>Default case</div>}>
  <Match when={condition1}>
    <div>Case 1</div>
  </Match>
  <Match when={condition2}>
    <div>Case 2</div>
  </Match>
</Switch>;

Suspense

import { Suspense } from "uele";

<Suspense fallback={<div>Loading...</div>}>{asyncComponent}</Suspense>;

Cleanup Support

Subscriptions and side-effects in UEle are automatically cleaned up when elements are garbage collected using FinalizationRegistry. You don't need to manually clean up unless desired, but it can be done through provided unsub functions.

Other Settings

UEle can be configured to work with any reactive library by setting the api object accordingly.

Refer more at usub

// preact/signals-core or usignal settings
api.effect = effect;
api.is = (v) => v instanceof Signal; // or preact signals
api.get = (v) => v?.value;

// oby or sinuous settings
api.effect = effect; // or api.effect = subscribe
api.is = (v) => isObservable(v); // or api.is = (v) => v?.$o;
api.get = (v) => v?.();

// solid-js settings
api.effect = createEffect;
api.is = (v) => v?.name?.includes("readSignal");
api.get = (v) => v?.();

For any other reactive library

Set the api object to match the library's functions:

import { api } from 'uele';

api.effect = ...; // Function to create an effect
api.is = (v) => ...; // Function to check if a value is reactive
api.get = (v) => ...; // Function to get the current value
api.cleanup = ...; // Explicit cleanup function for solid.js, sinuous and similar
api.any = ...; // Go crazy with anything.
api.diff = ...; // Any diffing library

Thanks and Inspiration

• bruh
• dy

License

MIT