epic-state
v0.13.0
Published
Reactive state management for frontend libraries.
Downloads
133
Maintainers
Readme
epic-state
Reactive state management for frontend libraries.
- Reactive values, actions and derived states
- Local and global plugins
- Navigatable state-tree structure
- Built-in TypeScript types
- Automatic
epic-jsx
and Preact integration without component wrapper - Map, Set support
Usage
Any root state has to be created from an object while the returned Proxy can be used like regular JavaScript values.
import { state } from 'epic-state'
const root = state({
count: 1,
nested: { count: 2 },
increment: () => {
root.count *= 2
},
get double() {
return root.count * 2
},
})
To connect the state to automatically rerender epic-jsx
components accessing the state add the following.
import { state, plugin } from 'epic-state'
import { connect } from 'epic-state/connect'
import { render } from 'epic-jsx'
plugin(connect) // Register global connect plugin for epic-jsx.
const root = state({
count: 1,
})
render(
<button
onClick={() => {
root.count += 1
}}
>
Increment {root.count}
</button>,
)
Observer
Using the observe method it's possible to receive notifications to state access or changes anywhere.
import { state, observe } from 'epic-state'
// TODO export observer type.
const myObserver = (action) => console.log(`Log: ${action}`)
const root = state({ count: 1 })
observe(myObserver)
// 'get' Action
const value = root.count // => Log: ['get', ['count'], 1]
// 'set' Action
root.count = 2 // => Log: ['get', ['count'], 2, 1]
// 'delete' Action
delete root.count // => Log: ['delete', ['count'], 2]
Data Structures
Using the observe method it's possible to receive notifications to state access or changes anywhere.
import { state, list } from 'epic-state'
const task = (name: string) => ({ name, done: false })
const root = state({ tasks: list(task, ['First Task', 'Second Task']) })
Plugins
Plugins - much like an observer - receive updates to the state but plugins can also be applied locally and defined for specific actions.
import { state, plugin } from 'epic-state'
import { connect } from 'epic-state/connect' // For epic-jsx
import { connect } from 'epic-state/preact' // For Preact
import { persistUrl } from 'epic-state/persist'
// Register plugin globally to any state updates.
plugin(connect)
// Add plugin to a local state.
const root = state({ count: 1, plugin: [connect] })
// Connect with configuration.
const root = state({ count: 1, page: 0, user: '123', plugin: [connect('page', 'user')] })
Build Your Own Plugin
Having access to state actions it's possible to encapsulate functionality as a plugin without the need for any changes to the regularly used code.
import { type Plugin, PluginActions } from 'epic-state'
function myConfigurableLogPlugin(...configuration: string[]): Plugin {
let properties: string[] = []
const isPropertyIgnored = () => properties.length !== 0 && !properties.includes(property)
const actions = {
get: ({ property, value }) =>
!isPropertyIgnored(property) && console.log(`GET: ${property} as ${value}`),
set: ({ property, value, previousValue }) => {
if (value === previousValue || isPropertyIgnored(property)) return
console.log(`SET: ${property} as ${value} from ${previousValue}`)
},
delete: ({ property }) =>
!isPropertyIgnored(property) && console.log(`DELETE: ${property}`),
} as PluginActions
// Called last by the library when a plugin is added to the state.
if (configuration[0] === 'initialize') {
return actions
}
properties = properties.concat(configuration ?? [])
return (...innerConfiguration: any) => {
// Plugin should only be configured once.
if (innerConfiguration[0] !== 'initialize') {
console.error('Plugin has already been configured')
}
return actions
}
}