choo

:steam_locomotive::train::train::train::train::train:

Fun functional programming

A 4kb framework for creating sturdy frontend applications

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_{The little framework that could. Built with ❤︎ by
Yoshua Wuyts and

contributors}

## Table of Content - [Features](#features) - [Example](#example) - [Philosophy](#philosophy) - [Optimizations](#optimizations) - [FAQ](#faq) - [API](#api) - [Installation](#installation) - [See Also](#see-also) - [Support](#support) ## Features - __minimal size:__ weighing `4kb`, `choo` is a tiny little framework - __event based:__ our performant event system makes writing apps easy - __small api:__ with only 6 methods there's not much to learn - __minimal tooling:__ built for the cutting edge `browserify` compiler - __isomorphic:__ renders seamlessly in both Node and browsers - __very cute:__ choo choo! ## Example ```js var html = require('choo/html') var choo = require('choo') var app = choo() app.use(logger) app.use(countStore) app.route('/', mainView) app.mount('body') function mainView (state, emit) { return html`

count is ${state.count}

` function onclick () { emit('increment', 1) } } function logger (state, emitter) { emitter.on('*', function (messageName, data) { console.log('event', messageName, data) }) } function countStore (state, emitter) { state.count = 0 emitter.on('increment', function (count) { state.count += count emitter.emit('render') }) } ``` Want to see more examples? Check out the [Choo handbook][handbook]. ## Philosophy We believe programming should be fun and light, not stern and stressful. It's cool to be cute; using serious words without explaining them doesn't make for better results - if anything it scares people off. We don't want to be scary, we want to be nice and fun, and then _casually_ be the best choice around. _Real casually._ We believe frameworks should be disposable, and components recyclable. We don't want a web where walled gardens jealously compete with one another. By making the DOM the lowest common denominator, switching from one framework to another becomes frictionless. Components should run anywhere that has a DOM, regardless of the framework. `choo` is modest in its design; we don't believe it will be top of the class forever, so we've made it as easy to toss out as it is to pick up. We don't believe that bigger is better. Big APIs, large complexities, long files - we see them as omens of impending userland complexity. We want everyone on a team, no matter the size, to fully understand how an application is laid out. And once an application is built, we want it to be small, performant and easy to reason about. All of which makes for easy to debug code, better results and super smiley faces. ## Optimizations Choo is reasonably fast out of the box. But sometimes you might hit a scenario where a particular part of the UI slows down the application, and you want to speed it up. Here are some optimizations that are possible. ### Reordering lists To be implemented. (See [yoshuawuyts/nanomorph#8](https://github.com/yoshuawuyts/nanomorph/issues/8)) ### Caching DOM elements Sometimes we want to tell the algorithm to not evaluate certain nodes (and its children). This can be because we're sure they haven't changed, or perhaps because another piece of code is managing that part of the DOM tree. To achieve this `nanomorph` evaluates the `.isSameNode()` method on nodes to determine if they should be updated or not. ```js var el = html`

node

` // tell nanomorph to not compare the DOM tree if they're both divs el.isSameNode = function (target) { return (target && target.nodeName && target.nodeName === 'DIV') } ``` ### Pruning dependencies We use the `require('assert')` module from Node core to provide helpful error messages in development. In production you probably want to strip this using [unassertify][unassertify]. To convert inlined HTML to valid DOM nodes we use `require('bel')`. This has overhead during runtime, so for production environments we should unwrap this using [yo-yoify][yo-yoify]. Setting up browserify transforms can sometimes be a bit of hassle; to make this more convenient we recommend using [bankai][bankai] with `--optimize` to compile your assets for production. ## FAQ ### Why is it called choo? Because I thought it sounded cute. All these programs talk about being _"performant"_, _"rigid"_, _"robust"_ - I like programming to be light, fun and non-scary. `choo` embraces that. Also imagine telling some business people you chose to rewrite something critical for serious bizcorp using a train themed framework. :steam_locomotive::train::train::train: ### Is it called choo, choo.js or...? It's called "choo", though we're fine if you call it "choo-choo" or "chugga-chugga-choo-choo" too. The only time "choo.js" is tolerated is if / when you shimmy like you're a locomotive. ### Does choo use a virtual-dom? `choo` uses [nanomorph][nanomorph], which diffs real DOM nodes instead of virtual nodes. It turns out that [browsers are actually ridiculously good at dealing with DOM nodes][morphdom-bench], and it has the added benefit of working with _any_ library that produces valid DOM nodes. So to put a long answer short: we're using something even better. ### How can I support older browsers? Template strings aren't supported in all browsers, and parsing them creates significant overhead. To optimize we recommend running `browserify` with [yo-yoify][yo-yoify] as a global transform or using [bankai][bankai] directly. ```sh $ browserify -g yo-yoify ``` ### Is choo production ready? Sure. ## API This section provides documentation on how each function in `choo` works. It's intended to be a technical reference. If you're interested in learning choo for the first time, consider reading through the [handbook][handbook] first :sparkles: ### `app = choo([opts])` Initialize a new `choo` instance. `opts` can also contain the following values: - __opts.history:__ default: `true`. Listen for url changes through the history API. - __opts.href:__ default: `true`. Handle all relative `` clicks and call `emit('render')` - __opts.timing:__ default: `true`. Enables calls to the [window.performance][window-performance] timing API. Timing calls will not run in browsers that don't support it out of the box. The timing marks are `choo:renderStart`, `choo:renderEnd`. The resulting diff is stored as `choo:render`. ### `app.use(callback(state, emitter))` Call a function and pass it a `state` and `emitter`. `emitter` is an instance of [nanobus](https://github.com/yoshuawuyts/nanobus/). You can listen to messages by calling `emitter.on()` and emit messages by calling `emitter.emit()`. Choo fires messages when certain events happen: - __`.on('DOMContentLoaded')`__: when the DOM has succesfully finished loading - __`.on('render')`__: when the DOM re-renders - __`.on('pushState')`__: when the history API is triggered ### `app.route(routeName, handler)` Register a route on the router. Uses [nanorouter][nanorouter] under the hood. Params can be registered by prepending the routename with `:routename`, e.g. `/foo/:bar/:baz`. The value of the param will be saved on `state.params` (e.g. `state.params.bar`). Wildcard routes can be registered with `*`, e.g. `/foo/*`. The value of the wildcard will be saved under `state.params.wildcard`. Using hashes to delimit routes is supported out of the box (e.g. `/foo#bar`). When a hash is found we also check if there's an available anchor on the same page, and will scroll the screen to the position. Using both hashes in URLs and anchor links on the page is generally not recommended. New routes can be triggered through `emitter.emit('pushState', )`. By default we also catch and match all `` clicks against the router. This can be disabled by setting `opts.href` to `false` in the constructor. Querystrings (`?foo=bar`) are ignored when matching routes. They should be extracted from the `window.location` object on render events, from either a custom event listener or the matched views. ### `app.mount(selector)` Start the application and mount it on the given `querySelector`. Uses [nanomount][nanomount] under the hood. This will _replace_ the selector provided with the tree returned from `app.start()`. If you want to add the app as a child to an element, use `app.start()` to obtain the tree and manually append it. ### `tree = app.start()` Start the application. Returns a tree of DOM nodes that can be mounted using `document.body.appendChild()`. ### `app.toString(location, [state])` Render the application to a string. Useful for rendering on the server. ### `choo/html` Create DOM nodes from template string literals. Exposes [bel](https://github.com/shama/bel). Can be optimized using [yo-yoify][yo-yoify]. ## Installation ```sh $ npm install choo ``` ## See Also - [bankai](https://github.com/yoshuawuyts/bankai) - streaming asset compiler - [stack.gl](http://stack.gl/) - open software ecosystem for WebGL - [yo-yo](https://github.com/maxogden/yo-yo) - tiny library for modular UI - [bel](https://github.com/shama/bel) - composable DOM elements using template strings - [tachyons](https://github.com/tachyons-css/tachyons) - functional CSS for humans - [sheetify](https://github.com/stackcss/sheetify) - modular CSS bundler for `browserify` ## Support Creating a quality framework takes a lot of time. Unlike others frameworks, Choo is completely independently funded. We fight for our users. This does mean however that we also have to spend time working contracts to pay the bills. This is where you can help: by chipping in you can ensure more time is spent improving Choo rather than dealing with distractions. ### Sponsors Become a sponsor and help ensure the development of independent quality software. You can help us keep the lights on, bellies full and work days sharp and focused on improving the state of the web. [Become a sponsor](https://opencollective.com/choo#sponsor)

### Backers Become a backer, and buy us a coffee (or perhaps lunch?) every month or so. [Become a backer](https://opencollective.com/choo#backer)

## License [MIT](https://tldrlegal.com/license/mit-license) [bankai]: https://github.com/yoshuawuyts/bankai [bel]: https://github.com/shama/bel [browserify]: https://github.com/substack/node-browserify [budo]: https://github.com/mattdesl/budo [es2020]: https://github.com/yoshuawuyts/es2020 [handbook]: https://github.com/yoshuawuyts/choo-handbook [hyperx]: https://github.com/substack/hyperx [morphdom-bench]: https://github.com/patrick-steele-idem/morphdom#benchmarks [nanomorph]: https://github.com/yoshuawuyts/nanomorph [nanorouter]: https://github.com/yoshuawuyts/nanorouter [nanomount]: https://github.com/yoshuawuyts/nanomount [yo-yo]: https://github.com/maxogden/yo-yo [yo-yoify]: https://github.com/shama/yo-yoify [unassertify]: https://github.com/unassert-js/unassertify [window-performance]: https://developer.mozilla.org/en-US/docs/Web/API/Performance