@b9g/crank

Crank.js

The Just JavaScript web framework.

Crank is a web framework where components can be defined with sync functions, async functions and generator functions. The documentation for Crank.js is available at crank.js.org.

Get Started

Crank.js is published on NPM under the @b9g organization (short for “bikeshaving”).

$ npm i @b9g/crank

Key Examples

A Simple Component

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

function Greeting({name = "World"}) {
  return (
    <div>Hello {name}</div>
  );
}

renderer.render(<Greeting />, document.body);

A Stateful Component

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

function *Timer() {
  let seconds = 0;
  const interval = setInterval(() => {
    seconds++;
    this.refresh();
  }, 1000);
  try {
    while (true) {
      yield <div>Seconds: {seconds}</div>;
    }
  } finally {
    clearInterval(interval);
  }
}

renderer.render(<Timer />, document.body);

An Async Component

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

async function QuoteOfTheDay() {
  const res = await fetch("https://favqs.com/api/qotd");
  const {quote} = await res.json();
  return (
    <p>
      “{quote.body}” – <a href={quote.url}>{quote.author}</a>
    </p>
  );
}

renderer.render(<QuoteOfTheDay />, document.body);

A Loading Component

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

async function LoadingIndicator() {
  await new Promise(resolve => setTimeout(resolve, 1000));
  return <div>Fetching a good boy...</div>;
}

async function RandomDog({throttle = false}) {
  const res = await fetch("https://dog.ceo/api/breeds/image/random");
  const data = await res.json();
  if (throttle) {
    await new Promise(resolve => setTimeout(resolve, 2000));
  }

  return (
    <a href={data.message}>
      <img src={data.message} alt="A Random Dog" width="300" />
    </a>
  );
}

async function *RandomDogLoader({throttle}) {
  for await ({throttle} of this) {
    yield <LoadingIndicator />;
    yield <RandomDog throttle={throttle} />;
  }
}

function *RandomDogApp() {
  let throttle = false;
  this.addEventListener("click", (ev) => {
    if (ev.target.tagName === "BUTTON") {
      throttle = !throttle;
      this.refresh();
    }
  });

  for ({} of this) {
    yield (
      <Fragment>
        <div>
          <button>Show me another dog.</button>
        </div>
        <RandomDogLoader throttle={throttle} />
      </Fragment>
    );
  }
}

renderer.render(<RandomDogApp />, document.body);

Changelog

[0.5.3] - 2023-03-12

Bug Fixes

• The cleanup() functions will be called even if components are unmounted. https://github.com/bikeshaving/crank/issues/249
• Fixes a situation where component errors in async components were being ignored. https://github.com/bikeshaving/crank/issues/253