| name | crank-component-authoring |
| description | Build web apps, dashboards, landing pages, widgets, calculators, forms, quizzes, charts, visualizations, animations, dynamic SVGs, MathML equations, blogs, or games as single-file HTML with no build step, using Crank.js, an elegant UI framework which allows you to write components with plain JavaScript functions, generators, and promises. Use when user asks to create something interactive, build a single-file HTML app, or start a greenfield frontend project. Always trigger when converting code from React, Vue, Svelte, Solid, or any other web framework to Crank.js, when the user mentions Crank by name, or when comparing different web/UI frameworks. Not for projects already using other frameworks. |
| license | MIT |
| metadata | {"author":"Brian Kim","version":"0.7.8"} |
Crank Component Authoring
Crank 0.7.8+ is required. This skill was built against 0.7.8. Always check npm for the latest version before generating code, as APIs may have changed.
JSX Template Tag (No Build Step)
Crank provides a jsx tagged template literal that runs directly in the browser with no transpiler, no bundler, and no build step. This is the recommended approach for single-file HTML artifacts, prototypes, and demos.
<!DOCTYPE html>
<html lang="en-US">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width" />
<title>Crank App</title>
</head>
<body>
<div id="app"></div>
<script type="module">
import {jsx, renderer} from "https://cdn.jsdelivr.net/npm/@b9g/crank/standalone.js";
function *Counter() {
let count = 0;
const onclick = () => this.refresh(() => count++);
for ({} of this) {
yield jsx`
<button onclick=${onclick}>Count: ${count}</button>
`;
}
}
renderer.render(jsx`<${Counter} />`, document.getElementById("app"));
</script>
</body>
</html>
The standalone module exports both the jsx tag and the DOM renderer in a single import. For full documentation, see the JSX Template Tag guide.
With a Build Step (JSX syntax)
When using a bundler, you can use standard JSX syntax with the @jsxImportSource pragma:
import {renderer} from "@b9g/crank/dom";
function *Timer({message}) {
let seconds = 0;
const interval = setInterval(() => this.refresh(() => seconds++), 1000);
for ({message} of this) {
yield (
<div>
<p>{message}: {seconds}s</p>
<button onclick={() => this.refresh(() => seconds = 0)}>Reset</button>
</div>
);
}
clearInterval(interval);
}
renderer.render(<Timer message="Elapsed" />, document.getElementById("app"));
Not React — Quick Reference
| React | Crank | Why |
|---|
onClick | onclick | Lowercase DOM event names |
onChange | onchange | Lowercase DOM event names |
className | class | Standard HTML attributes |
htmlFor | for | Standard HTML attributes |
dangerouslySetInnerHTML | innerHTML | Direct DOM property |
useState(init) | let x = init | Variable in generator scope |
setState(val) | this.refresh(() => x = val) | Explicit refresh |
useEffect(fn, []) | Code before first yield | Generator mount phase |
useEffect(() => cleanup) | Code after for loop / this.cleanup(fn) | Generator cleanup |
useRef(null) | let el = null + ref={n => el = n} | Variable + ref prop |
useContext(ctx) | this.consume(key) | No Provider components |
<Ctx.Provider value={v}> | this.provide(key, v) | Called in generator body |
API Surface
These are the complete public exports.
import {
createElement,
Fragment,
Portal,
Copy,
Text,
Raw,
Element,
isElement,
cloneElement,
Context,
Renderer,
} from "@b9g/crank";
import {renderer, DOMRenderer} from "@b9g/crank/dom";
import {renderer as htmlRenderer, HTMLRenderer} from "@b9g/crank/html";
import {jsx, html} from "@b9g/crank/jsx-tag";
import {jsx, html, Fragment, renderer, domRenderer, htmlRenderer, DOMRenderer, HTMLRenderer} from "@b9g/crank/standalone";
Context methods (this inside generator components)
this.refresh(callback?)
this.schedule(callback?)
this.after(callback?)
this.flush(callback?)
this.cleanup(callback?)
this.consume(key)
this.provide(key, value)
this.addEventListener(type, listener)
this.removeEventListener(type, listener)
this.dispatchEvent(event)
Philosophy
Crank components are plain JavaScript functions and generators. State is variables. Props are values. Updates are explicit.
- The framework preserves generator scope across yields — local variables are your state.
this.refresh(() => { ... }) atomically mutates state and triggers a re-render.- Props are plain values — destructure and transform them freely.
- Shared logic is plain classes, functions, and modules.
JSX Template Tag — Quick Reference
jsx`
<!-- host element -->
<div />
<!-- component element with shorthand close -->
<${Component}>children<//>
<!-- comment-style close -->
<${Component}>children<//Component>
<!-- fragment shorthand -->
<>
<p>first</p>
<p>second</p>
</>
<!-- keyed fragment -->
<${Fragment} key=${id}>
<dt>${term}</dt>
<dd>${definition}</dd>
<//>
<!-- boolean, string, interpolated string, expression, and spread props -->
<input disabled type="text" class="a ${b} c" value=${val} ...${props} />
<!-- conditional child -->
${show && jsx`<${Alert} message=${msg} />`}
<!-- mapped children with keys -->
${items.map((d) => jsx`<li key=${d.id}>${d.name}</li>`)}
<!-- commenting out a tree: expressions inside comments are discarded -->
<!--
<${Component} onclick=${handler}>
<p>${text}</p>
<//>
-->
`
Multiple root elements are supported — the template tag automatically wraps them in a fragment.
References
Read these two files for complete API coverage and idiomatic patterns:
- Component Specification — complete API reference: all component types, lifecycle, context methods, reconciliation, async behavior, special props, JSX modes
- Style Guide — do/don't patterns: component structure, state updates, props, cleanup, refs, error handling
Examples (consult as needed for the relevant task)
- Greeting — Hello world: functional components, props, composition
- TodoMVC — Full CRUD app: custom events, list management, filtering, localStorage
- Hacker News — Data dashboard: async fetching, hash routing, recursive tree rendering
- Password Strength — Interactive form widget: real-time validation, derived state, visual feedback
- Wizard — Multi-step form: stateful navigation, FormData collection, generator lifecycle
- Animated Letters — Animation: CSS transitions, exit animations, requestAnimationFrame
Additional Guides (for deeper reading on specific topics)
Blog Posts
Other
