vfunc

vfunc.js

UI as plain functions. No build, no virtual DOM — one script file.

한국어

Status: in development (Phase 0). The first public release (1.0) is being prepared. The API described here is planned and may change until 1.0.

vfunc.js is a small vanilla JavaScript library for building interactive pages and single-page apps. Its core idea: keep your HTML as it is, and turn only the parts you need to control into vfunc components.

• No build step — load one <script> and start. No bundler, no JSX, no transpiler.
• Works with published HTML — attach behavior to markup your designers or publishers already made.
• Easy for AI to write — a small, explicit API (state, render, delegates, methods) that language models generate correctly. Prompts and an llms.txt reference ship with the project.
• SPA ready — a tiny router, store, and i18n are included.
• Design-independent — logic and design are separated, so a design can be applied later by changing CSS tokens only.

Planned usage

<div id="counter"></div>
<script src="https://cdn.jsdelivr.net/npm/vfunc@1.0.0/dist/vfunc.min.js"
        integrity="sha384-..." crossorigin="anonymous"></script>
<script src="app.js"></script>

// app.js
const counter = vf.vfunc({
  state: { count: 0 },
  render: (s) => vf.html`<button data-action="inc">Clicked ${s.count} times</button>`,
  delegates: [{ selector: '[data-action="inc"]', eventType: 'click',
                onEvent: (e) => e.sender.setState({ count: e.sender.state.count + 1 }) }]
});
counter.mount(document.getElementById('counter'));

Layers

Browser support

Current versions of Chrome, Edge, Firefox and Safari. A separate legacy build (vfunc.legacy.min.js) is planned for Internet Explorer 11 and Edge IE mode.

Contributing and security

• CONTRIBUTING.md — contributions are accepted under the DCO (Signed-off-by).
• EXTENDING.md — how to extend vfunc without modifying it.
• SECURITY.md — report vulnerabilities privately, not in public issues.

License

Apache License 2.0. If you redistribute vfunc.js, keep the header comment in the distributed files and the NOTICE file.