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object-path-immutable
===========

Tiny JS library to modify deep object properties without modifying the original object (immutability).
Works great with React (especially when using `setState()`) and Redux (inside a reducer).

This can be seen as a simpler and more intuitive alternative to the *React Immutability Helpers* and *Immutable.js*.

## Changelog

[View Changelog](CHANGELOG.md)

## Install

    npm install object-path-immutable --save

## Quick usage

The following, sets a property without modifying the original object.
It will minimize the number of clones down the line. The resulting object is just a plain JS object literal,
so be warned that it will not be protected against property mutations (like `Immutable.js`)

```javascript
const obj = {
  a: {
    b: 'c',
    c: ['d', 'f']
  }
}

const newObj = immutable.set(obj, 'a.b', 'f')
// {
//   a: {
//     b: 'f',
//     c: ['d', 'f']
//   }
// }

// obj !== newObj
// obj.a !== newObj.a
// obj.a.b !== newObj.a.b

// However:
// obj.a.c === newObj.a.c
```

### Wrap mode

You can also chain the api's and call `value()` at the end to retrieve the resulting object.

```javascript
const newObj = immutable.wrap(obj).set('a.b', 'f').del('a.c.0').value()
```

## API

```javascript
// Premises

const obj = {
  a: {
    b: 'c',
    c: ['d', 'f']
  }
}

import * as immutable from 'object-path-immutable'
```

#### set (initialObject, path, value)

Changes an object property.

- Path can be either a string or an array.

```javascript
const newObj1 = immutable.set(obj, 'a.b', 'f')
const newObj2 = immutable.set(obj, ['a', 'b'], 'f')

// {
//   a: {
//     b: 'f',
//     c: ['d', 'f']
//   }
// }

// Note that if the path is specified as a string, numbers are automatically interpreted as array indexes.

const newObj = immutable.set(obj, 'a.c.1', 'fooo')
// {
//   a: {
//     b: 'f',
//     c: ['d', 'fooo']
//   }
// }
```

#### update (initialObject, path, updater)

Updates an object property.

```javascript
const obj = {
  a: {
    b: 1
  }
}

const newObj = immutable.update(obj, ['a', 'b'], v => v + 1)

// {
//   a: {
//     b: 2,
//   }
// }
```

#### push (initialObject, path, value)

Push into a deep array (it will create intermediate objects/arrays if necessary).

```javascript
const newObj = immutable.push(obj, 'a.d', 'f')
// {
//   a: {
//     b: 'f',
//     c: ['d', 'f'],
//     d: ['f']
//   }
// }
```

#### del (initialObject, path)

Deletes a property.

```javascript
const newObj = immutable.del(obj, 'a.c')
// {
//   a: {
//     b: 'f'
//   }
// }
```

Can also delete a deep array item using splice

```javascript
const newObj = immutable.del(obj, 'a.c.0')
// {
//   a: {
//     b: 'f',
//     c: ['f']
//   }
// }
```

#### assign (initialObject, path, payload)

Shallow copy properties.

```javascript
const newObj = immutable.assign(obj, 'a', { b: 'f', g: 'h' })
// {
//   a: {
//     b: 'f',
//     c: ['d, 'f'],
//     g: 'h'
//   }
// }
```

#### insert (initialObject, path, payload, position)

Insert property at the specific array index.

```javascript
const newObj = immutable.insert(obj, 'a.c', 'k', 1)
// var obj = {
//   a: {
//     b: 'c',
//     c: ['d, 'k' 'f'],
//   }
// }
```


#### merge (initialObject, path, value)

Deep merge properties.

```javascript
const newObj = immutable.merge(obj, 'a.c', {b: 'd'})
```

### Getters (not available in wrap mode)

#### get (object, path, defaultValue)

Retrieve a deep object property. Imported from [object-path](https://github.com/mariocasciaro/object-path) for convenience.

## Equivalent library with side effects

[object-path](https://github.com/mariocasciaro/object-path)