juicr.js

juicr.js

A simple (and tiny ~1kb) redux inspired reducer for handling state, actions, reactions etc. Works well with React.js & React Native but can be combined with any front end library.

Why?

I liked the redux pattern but the amount of boiler plate seemed overkill, especially for smaller projects.

Examples

All examples use the same juicr reducer code.

• React.js Todo
• Vanilla JS Todo
• Reef.js Todo

Setup

Add the package to your project either with:

# npm
npm install juicr.js

# yarn
yarn add juicr.js

or for browsers:

<script src="https://cdn.jsdelivr.net/npm/juicr.js" >

Simple example

1. Create a new Juicr with some initial state:

const juicr = new Juicr({ initialState: { count: 0 } })

1. Add an action with a name and a function that returns the changed state:

juicr.action("count", (amount, _state) => {
	return { count: _state.count += amount }
})

1. Listen to state changes. You can either listen to a single property, an array or use * to listen to all changes:

juicr.listen("*", (changedState, _state) => {
	document.body.innerHTML = changedState.count
	/* or your front end library update function e.g. this.setState({ ...changedState }) */
})

1. Dispatch actions to the Juicr:

setInterval(() => {
	juicr.dispatch("count", 1)
}, 1000)

Play with this example in CodePen.

For use with React see: Use with React & React Native

API

new Juicr({ initialState={}, dev=false })

Initializes a new Juicr. Pass in an initialState object and an optional dev flag. When dev mode is enabled all changes to the state are printed to the console.

juicr.action('actionName', (data, _state) => { })

Adds a dispatchable action to the Juicr. Specify the actionName and a function that returns the state changes. The data is passed in from the dispatch call as well as the current Juicr _state. For example:

juicr.action('delete', ({ id }, _state) => {
	return { items: _state.items.filter(t => t.id !== id ) }
})

juicr.dispatch('actionName', data)

Dispatches an action with data on your Juicr. For example:

juicr.dispatch("delete", { id: 1 })

juicr.listen('propName', (changedState, _state) => { })

Listens to changes to the state either from an action, or a reaction. You can either specify a single property:

juicr.listen("items", (changedState, _state) => { })

An array of properties:

juicr.listen(["propA", "propB"], (changedState, _state) => {})

Or use the special character * to listen to any changes on the state:

juicr.listen("*", (changedState, _state) => {})

juicr.reaction('propName', (changedState, _state) => { })

Reacts to changes in the state and returns new state changes, essentially like a computed property. Similar to listen you can react to changes on a single property, an array of properties, or any change using *.

juicr.reaction('count', ({ count }, _state) => {
	return { countIsPositive: count > 0 }
})

Asynchronous actions

Actions can return a Promise which resolves with the state changes. When dispatching use .then for triggering other actions or .catch for errors. Eg.

juicr.action("setText", (text) => {
	return new Promise((resolve) => {
		setTimeout(() => {
			resolve({ text })
		}, 100)
	})
})

juicr.dispatch("setLoading", true)
juicr.dispatch("setText", "hello").then((changedState) => {
	juicr.dispatch("setLoading", false)
	// changedState.text === "hello"
})

Multiple Juicrs

Larger projects may benefit from using multiple Juicrs for different parts of your application data. For example you might have one Juicr for the user state and another for a list of todos.

Use with React & React Native

Using juicr.js with React.js & React Native is easy. The simplest approach is to listen to all changes * in your main app component and use setState to update your state:

// App.js
constructor() {
	...
    this.juicr.listen("*", (changedState, _state) => {
      this.setState({ ...changedState })
    })
    ...
}

Then pass the juicr.dispatch function to components:

<MyComponent dispatch={this.juicr.dispatch} />

Alternatively you could pass the entire juicr to your components and let them handle their own internal state and listen for changes, e.g:

// UserHeader.js
constructor(props) {
	...
	this.state = { username: '', photoUrl: '' }

	props.userJuicr.listen(["username", "photoUrl", (changedState, _state) => {
		this.setState({ ...changedState })
	})
	...
}