useList
useList(store, renderItem)
Hook function for efficient rendering of list store. Every item will be memoized and updated only when their data changes.
Arguments
store(Store): Store should be arrayrenderItem(Function): Render function which will be called for every item in list
Returns
(React.Node)
Example
import React from 'react'
import ReactDOM from 'react-dom'
import {createStore} from 'effector'
import {useList} from 'effector-react'
const users = createStore([
{id: 1, name: 'Yung'},
{id: 2, name: 'Lean'},
{id: 3, name: 'Kyoto'},
{id: 4, name: 'Sesh'},
])
const Users = () => {
// we don't need keys here any more
const list = useList(users, ({name}, index) => (
<li>
[{index}] {name}
</li>
))
return <ul>{list}</ul>
}
ReactDOM.render(<Users />, document.getElementById('root'))
import React from 'react'
import ReactDOM from 'react-dom'
import {createStore, createEvent} from 'effector'
import {useList} from 'effector-react'
const addTodo = createEvent()
const toggleTodo = createEvent()
const todoList = createStore([
{text: 'write useList example', done: true},
{text: 'update readme', done: false},
])
.on(toggleTodo, (list, id) =>
list.map((todo, i) => {
if (i === id)
return {
...todo,
done: !todo.done,
}
return todo
}),
)
.on(addTodo, (list, e) => [
...list,
{
text: e.currentTarget.elements.content.value,
done: false,
},
])
addTodo.watch(e => {
e.preventDefault()
})
const TodoList = () =>
useList(todoList, ({text, done}, i) => {
const todo = done ? (
<del>
<span>{text}</span>
</del>
) : (
<span>{text}</span>
)
return <li onClick={() => toggleTodo(i)}>{todo}</li>
})
const App = () => (
<div>
<h1>todo list</h1>
<form onSubmit={addTodo}>
<label htmlFor="content">New todo</label>
<input type="text" name="content" required />
<input type="submit" value="Add" />
</form>
<ul>
<TodoList />
</ul>
</div>
)
By default, useList rerenders only when some of its items were changed. However, sometimes we need to update items when some external value (e.g. props field or state of another store) changes. In such case, we need to tell react about our dependencies and pass keys explicitly.
Example 2
import React from 'react'
import ReactDOM from 'react-dom'
import {createEvent, createStore, restore} from 'effector'
import {useStore, useList} from 'effector-react'
const renameUser = createEvent()
const user = restore(renameUser, 'alice')
const friends = createStore(['bob'])
const List = () => {
const userName = useStore(user)
return useList(friends, {
keys: [userName],
fn: friend => (
<div>
{friend} is a friend of {userName}
</div>
),
})
}
ReactDOM.render(<List />, document.getElementById('root'))
// => <div> bob is a friend of alice </div>
setTimeout(() => {
renameUser('carol')
// => <div> bob is a friend of carol </div>
}, 500)
useList(store, {keys, fn})
Used when you need to pass dependencies to react (to update items when some of its dependencies are changed)
Arguments
store(Store): Store should be arraykeys(Array): Array of dependencies, which will be passed to react byuseListfn(Function): Render function which will be called for every item in list
import {createStore} from 'effector'
import {useList} from 'effector-react'
export const friends = createStore(['alice', 'bob'])
export const FriendList = ({username}) => useList(friends, {
keys: [username],
fn: friend => (
<p>
{friend} is a friend of {username}
</p>
)
})