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0.4.7 • Public • Published

Longwood    Travis CI build status GitHub license npm version PRs Welcome

A simple user interface library


Longwood can be summarized with these three principles:

  1. It's just JavaScript
    This view library does not invent a new syntax for templating — you can use traditional Javascript without any build tools.
  2. Beginner friendly
    No magic. Longwood does not introduce complicated concepts that you'll need a PhD in computer science to understand.
  3. Strong Typescript support
    When you're ready, jump in with Typescript and have clear and strong types there to help you.


Longwood uses composition to describe component hierarchies. In practice, here's the "hello world" of Longwood:

const render = div(text('Hello world'))

▶️ Run in CodeSandbox.io

This creates a <div> element which has a child Text node containing "Hello world" and mounts the component inside <div id="app"> element.

Nesting components

You can nest multiple components:

const render = ul(li(text('Hello')), li(text('World')))

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Passing props

You have all common props from HTML element JS API available, and you can provide an pbject as the first argument to pass them in. In this case you'll need to use the named children prop to pass in the child components:

const render = div({
  children: [text('Hello world')],
  className: 'my-app'

▶️ Run in CodeSandbox.io


Components in Longwood are simply functions. You can split your components up without any overhead:

const Greet = ({ who }) => div(text(`Hello ${who}`))
const render = Greet({ who: 'world' })

▶️ Run in CodeSandbox.io

The beauty of this is, that (unlike with e.g. at React) these components will be treated as optimizable Javascript, so you can use UglifyJS to achieve zero-cost abstractions.

State management

Longwood does not force you to use any specific state handling, in fact it does not have any state handling built in, because state handling should not be part of a view library.

There are many great state handling libraries out there, and connecting any of those to Longwood is simple.

A simple asynchronous state

How do you update your dom after your state changes? You call the render again with fresh data:

export default function AsyncJoke({ joke }) {
  if (!joke) return div(text('Loading the joke...'))
  return div(div(text('The joke is here:')), div(text(joke)))

const target = document.getElementById('app')

const renderInitial = AsyncJoke({ joke: undefined })

fetchRandomJoke().then((joke) => {
  const renderWithJoke = AsyncJoke({ joke })

▶️ Run in CodeSandbox.io

Here the component renders a loading text first and then re-renders the result as soon as the request finishes.

This trivial example could be extended to use any general state management library instead of promises. You could use rxjs subscriptions, Redux selectors or Firebase listeners, and they are all as easy to implement as our little example.

For people coming from React there's longwood-usestate library that behaves close to how React's useState and useContext hooks do.

Getting started (ES Modules)

Longwood is available as ES module, so quickest way to get started is to import the module directly within your HTML page:

    <div id="app"></div>
    <script type="module">
      import { div, text } from 'https://cdn.skypack.dev/longwood'

      const render = div(text('Hello world!'))

▶️ Run in CodeSandbox.io

This is literally all the code you'll need! No build tools needed, no extra steps, just save the code as a .html file and start hacking.

Getting started (npm)

You can install Longwood to your project like a normal dependency within your project:

yarn add longwood

Then you can import the package in your js file. For example if you're using Webpack, you can do:

import { div } from 'longwood'

const render = div({ innerText: 'Hello world!' })


You can use TDD for development by running:

yarn test --watch

This runs Jest, and the tests use JSDOM for asserting how DOM looks like.


You can build the project by running:

yarn build

This builds the project into build/ directory.


This project is automatically deployed to NPM by using Travis CI. All tagged versions are published when pushed.

Don't add tags by hand! Run:

yarn release

This will run an interactive deploy script to help you deploy the most recent version.


This is a very early version of the project, and all feedback is welcome. Please open an issue before implementing, as the direction still needs some adjustments.


The code in this project is licensed under MIT license.




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