bikeshaving

crank-component-authoring

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.

bikeshaving 2,791 81 Updated 3mo ago
GitHub

Install

npx skillscat add bikeshaving/crank/crank-component-authoring

Install via the SkillsCat registry.

SKILL.md

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:

/** @jsxImportSource @b9g/crank */
import {renderer} from "@b9g/crank/dom";

function *Timer({message}) {
  let seconds = 0;
  // Mount: start interval
  const interval = setInterval(() => this.refresh(() => seconds++), 1000);

  // Update: loop receives fresh props on each re-render
  for ({message} of this) {
    yield (
      <div>
        <p>{message}: {seconds}s</p>
        <button onclick={() => this.refresh(() => seconds = 0)}>Reset</button>
      </div>
    );
  }

  // Cleanup: runs on unmount
  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.

// Core — components, elements, and rendering infrastructure
import {
  createElement,   // Create an element (called automatically by JSX)
  Fragment,         // Group children without a wrapper node ("")
  Portal,           // Render children into a different root node
  Copy,             // Reuse the previously rendered child tree
  Text,             // Render a text node with explicit text prop
  Raw,              // Insert raw HTML/markup via value prop
  Element,          // Element class (for type checking)
  isElement,        // Test if a value is a Crank element
  cloneElement,     // Clone an element with merged props
  Context,          // Component context class
  Renderer,         // Base renderer class (for custom renderers)
} from "@b9g/crank";

// DOM renderer
import {renderer, DOMRenderer} from "@b9g/crank/dom";

// HTML string renderer (SSR)
import {renderer as htmlRenderer, HTMLRenderer} from "@b9g/crank/html";

// JSX template tag (no build step)
import {jsx, html} from "@b9g/crank/jsx-tag";

// Standalone — re-exports everything above in one import
import {jsx, html, Fragment, renderer, domRenderer, htmlRenderer, DOMRenderer, HTMLRenderer} from "@b9g/crank/standalone";

Context methods (this inside generator components)

this.refresh(callback?)   // Mutate state and re-render
this.schedule(callback?)  // Run after this render commits (once)
this.after(callback?)     // Run after every render commits
this.flush(callback?)     // Run after the entire render tree commits
this.cleanup(callback?)   // Run on unmount
this.consume(key)         // Read a provided value from an ancestor
this.provide(key, value)  // Provide a value to descendants
this.addEventListener(type, listener)    // Listen for DOM or custom events
this.removeEventListener(type, listener) // Remove an event listener
this.dispatchEvent(event)               // Dispatch an event up the tree

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:

  1. Component Specification — complete API reference: all component types, lifecycle, context methods, reconciliation, async behavior, special props, JSX modes
  2. 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

Categories

UI Components
GitHub

Install

npx skillscat add bikeshaving/crank/crank-component-authoring

Install via the SkillsCat registry.

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