costate

Welcome to costate 👋

A state management library for react inspired by vue 3.0 reactivity api and immer

costate is a tiny package that allows you to work with immutable state in a more reactive way.

🏠 Homepage

Features

• mutate costate to derive the next immutable state reactively
• write code in idiomatic javascript style
• no need to centralize all of update-state/reducer function in React Component

Environment Requirement

• ES2015 Proxy
• ES0215 Map
• ES2015 Symbol

Can I Use Proxy?

Install

npm install --save costate

yarn add costate

API DOCS

Usage

import createCostate, { watch } from 'costate'

// costate is reactive
const costate = createCostate({ a: 1 })

// state is immutable
watch(costate, state => {
  console.log(`state.a is: ${state.a}`)
})

// mutate costate will emit the next immutable state to watcher
costate.a += 1

Why costate is useful?

Think about costate + react-hooks!

Counter

• demo
• source-code

import * as React from 'react'
import { co, useCostate } from 'costate'

function Counter() {
  // useCostate instead of React.useState
  // state is always immutable
  let state = useCostate({ count: 0 })

  let handleIncre = () => {
    // pass state to co, then got the costate which is reactive
    // mutate costate will cause re-render and receive the next state
    co(state).count += 1
  }

  let handleDecre = () => {
    co(state).count -= 1
  }

  return (
    <>
      <button onClick={handleIncre}>+1</button>
      {state.count}
      <button onClick={handleDecre}>-1</button>
    </>
  )
}

TodoApp

• demo
• source-code

export default function App() {
  // initialize todo-app state
  let state = useCostate({
    todos: [],
    text: {
      value: ''
    }
  })

  useSessionStorage({
    key: 'todos-json',
    getter: () => state,
    setter: source => Object.assign(co(state), source)
  })

  let handleAddTodo = () => {
    if (!state.text.value) {
      return alert('empty content')
    }

    // wrap by co before mutating
    co(state).todos.push({
      id: Date.now(),
      content: state.text.value,
      completed: false
    })
    co(state).text.value = ''
  }

  let handleKeyUp = event => {
    if (event.key === 'Enter') {
      handleAddTodo()
    }
  }

  let handleToggleAll = () => {
    let hasActiveItem = state.todos.some(todo => !todo.completed)
    // wrap by co before mutating
    co(state).todos.forEach(todo => {
      todo.completed = hasActiveItem
    })
  }

  return (
    <>
      <div>
        <TodoInput text={state.text} onKeyUp={handleKeyUp} />
        <button onClick={handleAddTodo}>add</button>
        <button onClick={handleToggleAll}>toggle-all</button>
      </div>
      <Todos todos={state.todos} />
      <Footer todos={state.todos} />
    </>
  )
}

function Todos({ todos }) {
  return (
    <ul>
      {todos.map(todo => {
        return <Todo key={todo.id} todo={todo} />
      })}
    </ul>
  )
}

function Todo({ todo }) {
  // you can create any costate you want
  // be careful, costate must be object or array
  let edit = useCostate({ value: false })
  let text = useCostate({ value: '' })

  let handleEdit = () => {
    // wrap by co before mutating
    co(edit).value = !edit.value
    co(text).value = todo.content
  }

  let handleEdited = () => {
    co(edit).value = false
    // magic happen!!
    // we don't need TodoApp to pass updateTodo function down to Todo
    // we just like todo is local state, wrap by co before mutating it
    // then it will cause TodoApp drived new state and re-render
    co(todo).content = text.value
  }

  let handleKeyUp = event => {
    if (event.key === 'Enter') {
      handleEdited()
    }
  }

  let handleRemove = () => {
    // we don't need TodoApp to pass removeTodo function down to Todo
    // cotodo can be delete by remove function
    remove(co(todo))
  }

  let handleToggle = () => {
    co(todo).completed = !todo.completed
  }

  return (
    <li>
      <button onClick={handleRemove}>remove</button>
      <button onClick={handleToggle}>{todo.completed ? 'completed' : 'active'}</button>
      {edit.value && <TodoInput text={text} onBlur={handleEdited} onKeyUp={handleKeyUp} />}
      {!edit.value && <span onClick={handleEdit}>{todo.content}</span>}
    </li>
  )
}

function TodoInput({ text, ...props }) {
  let handleChange = event => {
    co(text).value = event.target.value
  }
  return <input type="text" {...props} onChange={handleChange} value={text.value} />
}

function Footer({ todos }) {
  let activeItems = todos.filter(todo => !todo.completed)
  let completedItems = todos.filter(todo => todo.completed)

  let handleClearCompleted = () => {
    ;[...completedItems].reverse().forEach(item => remove(co(item)))
  }

  return (
    <div>
      {activeItems.length} item{activeItems.length > 1 && 's'} left |{' '}
      {completedItems.length > 0 && <button onClick={handleClearCompleted}>Clear completed</button>}
    </div>
  )
}

Caveat

• createCostate(state) only accept object or array as arguemnt

Author

👤 Jade Gu

• Twitter: @guyingjie129
• Github: @Lucifier129

🤝 Contributing

Contributions, issues and feature requests are welcome!

Feel free to check issues page.

Show your support

Give a ⭐️ if this project helped you!

📝 License

Copyright © 2019 Jade Gu.

This project is MIT licensed.

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