Longwood 
A simple user interface library
Principles
Longwood can be summarized with these three principles:
-
It's just JavaScript
This view library does not invent a new syntax for templating — you can use traditional Javascript without any build tools. -
Beginner friendly
No magic. Longwood does not introduce complicated concepts that you'll need a PhD in computer science to understand. -
Strong Typescript support
When you're ready, jump in with Typescript and have clear and strong types there to help you.
Example
Longwood uses composition to describe component hierarchies. In practice, here's the "hello world" of Longwood:
const render = div(text('Hello world'))
render(document.getElementById('app'))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')))
render(document.getElementById('app'))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'
})
render(document.getElementById('app'))Components
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' })
render(document.getElementById('app'))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 })
renderInitial(target)
fetchRandomJoke().then((joke) => {
const renderWithJoke = AsyncJoke({ joke })
renderWithJoke(target)
})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:
<html>
<body>
<div id="app"></div>
<script type="module">
import { div, text } from 'https://cdn.skypack.dev/longwood'
const render = div(text('Hello world!'))
render(document.getElementById('app'))
</script>
</body>
</html>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, text } from 'longwood'
const render = div(text('Hello world!'))
render(document.getElementById('app'))Developing
You can use TDD for development by running:
yarn
yarn test --watch
This runs Jest, and the tests use JSDOM for asserting how DOM looks like.
Building
You can build the project by running:
yarn buildThis builds the project into build/ directory.
Deploying
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 releaseThis will run an interactive deploy script to help you deploy the most recent version.
Contributing
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.
Licensing
The code in this project is licensed under MIT license.