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https://github.com/immerjs/use-immer

Use immer to drive state with a React hooks
https://github.com/immerjs/use-immer

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Use immer to drive state with a React hooks

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README

        

# use-immer

A hook to use [immer](https://github.com/mweststrate/immer) as a React [hook](https://reactjs.org/docs/hooks-intro.html) to manipulate state.

# Installation

`npm install immer use-immer`

# API

## useImmer

`useImmer(initialState)` is very similar to [`useState`](https://reactjs.org/docs/hooks-state.html).
The function returns a tuple, the first value of the tuple is the current state, the second is the updater function,
which accepts an [immer producer function](https://immerjs.github.io/immer/produce) or a value as argument.

### Managing state with immer producer function

When passing a function to the updater, the `draft` argument can be mutated freely, until the producer ends and the changes will be made immutable and become the next state.

Example: https://codesandbox.io/s/l97yrzw8ol

```javascript
import React from "react";
import { useImmer } from "use-immer";

function App() {
const [person, updatePerson] = useImmer({
name: "Michel",
age: 33
});

function updateName(name) {
updatePerson(draft => {
draft.name = name;
});
}

function becomeOlder() {
updatePerson(draft => {
draft.age++;
});
}

return (



Hello {person.name} ({person.age})


{
updateName(e.target.value);
}}
value={person.name}
/>


Older

);
}
```

(obviously, immer is a little overkill for this example)

### Managing state as simple useState hook
When passing a value to the updater instead of a function, `useImmer` hook behaves the same as useState hook and updates the state with that value.

```javascript
import React from 'react';
import { useImmer } from 'use-immer';

function BirthDayCelebrator(){
const [age, setAge] = useImmer(20);

function birthDay(event){
setAge(age + 1);
alert(`Happy birthday #${age} Anon! hope you good`);
}

return(


It is my birthday

);
}
```

Obviously if you have to deal with immutability it is better option passing a function to the updater instead of a direct value.

## useImmerReducer

Immer powered reducer, based on [`useReducer` hook](https://reactjs.org/docs/hooks-reference.html#usereducer)

Example: https://codesandbox.io/s/2zor1monvp

```javascript
import React from "react";
import { useImmerReducer } from "use-immer";

const initialState = { count: 0 };

function reducer(draft, action) {
switch (action.type) {
case "reset":
return initialState;
case "increment":
return void draft.count++;
case "decrement":
return void draft.count--;
}
}

function Counter() {
const [state, dispatch] = useImmerReducer(reducer, initialState);
return (
<>
Count: {state.count}
dispatch({ type: "reset" })}>Reset
dispatch({ type: "increment" })}>+
dispatch({ type: "decrement" })}>-
>
);
}
```