Reactive Web Components,
100% native JavaScript.
Ultima is a framework for building reusable components using only what the browser already
knows how to do — Custom Elements, Shadow DOM
and native ES modules. No build step, no npm install, no dependencies
loaded at runtime.
<div data-bind='{"textContent":"total"}'></div>
<button onclick="this.getRootNode().host.increment()">+1</button>
<!-- no build, no framework running underneath: it's just the browser reading the attribute -->Why Vanilla JS
The project's philosophy from day one: code that runs natively in the browser is a good practice, not a limitation.
Zero dependencies
No library is loaded from a CDN at runtime. What runs is exactly the
.js file you import — no bundler, no build step,
no node_modules.
Real Web standards
Components are real Custom Elements, with true optional
Shadow DOM — not an abstraction layered on top that looks like
Web Components. Interoperates with any other HTML/CSS/JS code.
Declarative reactivity
Attribute binding, conditionals, keyed lists, computed properties and watchers — right in
data-* attributes on your HTML, with no proprietary template
syntax to learn.
The syntax
A glimpse of the full vocabulary — conditional, keyed list and two-way binding, all in the same component.
<input data-bind='{"value":"newTask"}'>
<template data-if="tasks.length">
<ul>
<template data-for="task in tasks : id">
<li data-class='{"done":"task.done"}'>
<input type="checkbox" data-bind='{"checked":"task.done"}'>
<span data-bind='{"textContent":"task.title"}'></span>
</li>
</template>
</ul>
</template>
<template data-else>
<p>No tasks yet.</p>
</template>Where to go from here
Getting started →
How to add Ultima to a project and build your first reactive component, with nothing to install.
Guide →
The core concepts — ComponentBase and
ReactiveComponent, lifecycle, data scope.
DSL reference →
Every template attribute, with syntax and an example — the full showcase of the reactive vocabulary.
Examples →
A complete reactive form and the "Workspace" — the project's reference application, with treemap and windows.