Aberdeen

Build blazing-fast, reactive UIs in pure TypeScript/JavaScript – no virtual DOM.

Aberdeen offers a refreshingly simple approach to reactive UIs. Its core idea:

Use many small, anonymous functions for emitting DOM elements, and automatically rerun them when their underlying proxied data changes. This proxied data can be anything from simple values to complex, typed, and deeply nested data structures.

Now, let's dive into why this matters...

Why use Aberdeen?

🎩 Simple: Express UIs naturally in JavaScript/TypeScript, without build steps or JSX, and with a minimal amount of concepts you need to learn.
⏩ Fast: No virtual DOM. Aberdeen intelligently updates only the minimal, necessary parts of your UI when proxied data changes.
👥 Awesome lists: It's very easy and performant to reactively display data sorted by whatever you like.
🔬 Tiny: Around 5KB (minimized and gzipped) and with zero runtime dependencies.
🔋 Batteries included: Comes with client-side routing, revertible patches for optimistic user-interface updates, component-local CSS, helper functions for transforming reactive data (mapping, partitioning, filtering, etc) and hide/unhide transition effects. No bikeshedding required!

Why not use Aberdeen?

🤷 Lack of community: There are not many of us -Aberdeen developers- yet, so don't expect terribly helpful Stack Overflow/AI answers.
📚 Lack of ecosystem: You'd have to code things yourself, instead of duct-taping together a gazillion React ecosystem libraries.

Examples

First, let's start with the obligatory reactive counter example. If you're reading this on the official website you should see a working demo below the code, and an 'edit' button in the top-right corner of the code, to play around.

import {$, proxy, ref} from 'aberdeen';

// Define some state as a proxied (observable) object
const state = proxy({question: "How many roads must a man walk down?", answer: 42});

$('h3', () => {
    // This function reruns whenever the question or the answer changes
    $(`:${state.question} ↪ ${state.answer || 'Blowing in the wind'}`)
});

// Two-way bind state.question to an <input>
$('input', {placeholder: 'Question', bind: ref(state, 'question')})

// Allow state.answer to be modified using both an <input> and buttons
$('div.row', {$marginTop: '1em'}, () => {
    $('button:-', {click: () => state.answer--});
    $('input', {type: 'number', bind: ref(state, 'answer')})
    $('button:+', {click: () => state.answer++});
});

Okay, next up is a somewhat more complex app - a todo-list with the following behavior:

New items open in an 'editing state'.
Items that are in 'editing state' show a text input, a save button and a cancel button. Done status cannot be toggled while editing.
Pressing one of the buttons, or pressing enter will transition from 'editing state' to 'viewing state', saving the new label text unless cancel was pressed.
In 'viewing state', the label is shown as non-editable. There's an 'Edit' link, that will transition the item to 'editing state'. Clicking anywhere else will toggle the done status.
The list of items is sorted alphabetically by label. Items move when 'save' changes their label.
Items that are created, moved or deleted are grown and shrink as appropriate.

Pfew.. now let's look at the code:

import {$, proxy, onEach, insertCss, peek, observe, unproxy, ref} from "aberdeen";
import {grow, shrink} from "aberdeen/transitions";

// We'll use a simple class to store our data.
class TodoItem {
    constructor(public label: string = '', public done: boolean = false) {}
    toggle() { this.done = !this.done; }
}

// The top-level user interface.
function drawMain() {
    // Add some initial items. We'll wrap a proxy() around it!
    let items: TodoItem[] = proxy([
        new TodoItem('Make todo-list demo', true),
        new TodoItem('Learn Aberdeen', false),
    ]);
    
    // Draw the list, ordered by label.
    onEach(items, drawItem, item => item.label);

    // Add item and delete checked buttons.
    $('div.row', () => {
        $('button:+', {
            click: () => items.push(new TodoItem("")),
        });
        $('button.outline:Delete checked', {
            click: () => {
                for(let idx in items) {
                    if (items[idx].done) delete items[idx];
                }
            }
        });
    });
};

// Called for each todo list item.
function drawItem(item) {
    // Items without a label open in editing state.
    // Note that we're creating this proxy outside the `div.row` scope
    // create below, so that it will persist when that state reruns.
    let editing: {value: boolean} = proxy(item.label == '');

    $('div.row', todoItemStyle, {create:grow, destroy: shrink}, () => {
        // Conditionally add a class to `div.row`, based on item.done
        $({".done": ref(item,'done')});

        // The checkmark is hidden using CSS
        $('div.checkmark:✅');

        if (editing.value) {
            // Label <input>. Save using enter or button.
            function save() {
                editing.value = false;
                item.label = inputElement.value;
            }
            let inputElement = $('input', {
                placeholder: 'Label',
                value: item.label,
                keydown: e => e.key==='Enter' && save(),
            });
            $('button.outline:Cancel', {click: () => editing.value = false});
            $('button:Save', {click: save});
        } else {
            // Label as text. 
            $('p:' + item.label);

            // Edit icon, if not done.
            if (!item.done) {
                $('a:Edit', {
                    click: e => {
                        editing.value = true;
                        e.stopPropagation(); // We don't want to toggle as well.
                    },
                });
            }
            
            // Clicking a row toggles done.
            $({click: () => item.done = !item.done, $cursor: 'pointer'});
        }
    });
}

// Insert some component-local CSS, specific for this demo.
const todoItemStyle = insertCss({
    marginBottom: "0.5rem",
    ".checkmark": {
        opacity: 0.2,
    },
    "&.done": {
        textDecoration: "line-through",
        ".checkmark": {
            opacity: 1,
        },
    },
});

// Go!
drawMain();

Some further examples:

Learning Aberdeen

And you may want to study the examples above, of course!

News

2025-05-07: After five years of working on this library on and off, I'm finally happy with its API and the developer experience it offers. I'm calling it 1.0! To celebrate, I've created some pretty fancy (if I may say so myself) interactive documentation and a tutorial.