Immutable version of dot-prop with some extensions

Usage no npm install needed!

<script type="module">
  import dotPropImmutable from '';



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Immutable version of dot-prop with some extensions.

npm install dot-prop-immutable

The motivation for this module is to have a simple utility for changing state in a React-Redux application without mutating the existing state of plain JavaScript objects. If you are going for real immutable data collections take a look at the cool library Immutable.js. A good practice is not to mix the immutable data collections with mutable objects because it can lead to confusion. Immutable objects are not accessed by the default semantics, but implemented by setters and getters.

This library implements 3 helper functions:

get(object, path) --> value
set(object, path, value) --> object
delete(object, path) --> object

None of the functions mutate the input object. For efficiency, the returned object is not a deep clone of the original, but a shallow copy of the objects in the mutated path.


const dotProp = require('dot-prop-immutable');
let state = { todos: [] }, index = 0;

// Add todo:
state = dotProp.set(state, 'todos', list => [...list, {text: 'cleanup', complete: false}])
// or with destructuring assignment
state = {...state, todos: [...state.todos, {text: 'cleanup', complete: false}]};
//=>  { todos: [{text: 'cleanup', complete: false}] }

// Complete todo:
state = dotProp.set(state, `todos.${index}.complete`, true)
// or with destructuring assignment
state = {...state, todos: [
    ...state.todos.slice(0, index),
    {...state.todos[index], complete: true},
    ...state.todos.slice(index + 1)
//=>  { todos: [{text: 'cleanup', complete: true}] }

// Delete todo:
state = dotProp.delete(state, `todos.${index}`)
// or with destructuring assignment
state = {...state, todos: [
    ...state.todos.slice(0, index),
    ...state.todos.slice(index + 1)
//=>  { todos: [] }


Access a nested property by a dot path

// Getter
dotProp.get({foo: {bar: 'unicorn'}}, '')
//=> 'unicorn'

dotProp.get({foo: {bar: 'a'}}, 'foo.notDefined.deep')
//=> undefined

dotProp.get({foo: {bar: 'a'}}, 'foo.notDefined.deep', 'default value')
//=> default value

dotProp.get({foo: {'': 'unicorn'}}, '\\.dot')
//=> 'unicorn'

or use a property array as a path.

// Use an array as get path
dotProp.get({foo: {'': 'unicorn'}}, ['foo', ''])
//=> 'unicorn'

It is also possible to index into an array where the special index $end refers to the last element of the array.

const obj = {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn']};

// Index into array
dotProp.get(obj, 'foo.1')
//=> 'white-unicorn'

dotProp.get(obj, '')
//=> 'gold-unicorn'

// Index into array with $end
dotProp.get(obj, 'foo.$end')
//=> 'silver-unicorn'

// If obj is an array
dotProp.get([{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn'], '')
//=> 'gold-unicorn'


Modify a nested property by a dot path

// Setter
const obj = {foo: {bar: 'a'}};

const obj1 = dotProp.set(obj, '', 'b');
//obj1 => {foo: {bar: 'b'}}

const obj2 = dotProp.set(obj1 , 'foo.baz', 'x');
//obj2 => {foo: {bar: 'b', baz: 'x'}}

where obj, obj1, obj2, obj3 all are different objects.

Use a function to modify the selected property, where first argument is the old value.

// Setter where value is a function (get and set current value)
dotProp.set({foo: {bar: 'a'}}, '', v => v + 'bc')
//=> {foo: {bar: 'abc'}}

Modify a nested array

const obj = {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn']};

// Index into array
dotProp.set(obj, 'foo.1', 'platin-unicorn')
//=> {foo: [{bar: 'gold-unicorn'}, 'platin-unicorn', 'silver-unicorn']}

dotProp.set(obj, '', 'platin-unicorn')
//=> {foo: [{bar: 'platin-unicorn'}, 'white-unicorn', 'silver-unicorn']}

// Index into array with $end
dotProp.set(obj, 'foo.$end', 'platin-unicorn')
//=> {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'platin-unicorn']}


Delete a nested property/array by a dot path

const obj = {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn']};

// delete
dotProp.delete(obj, 'foo.$end');
//=> {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn']}

dotProp.delete(obj, '');
//=> {foo: [{}, 'white-unicorn', 'silver-unicorn']}


Toggle a boolean a value by a dot path.

const obj = {foo: { bar: true } };

// toggle
dotProp.toggle(obj, '');
//=> {foo: { bar: false } }


Merge a value by a dot path.

The target value must be an object, array, null, or undefined.

  • If target is an object, Object.assign({}, target, param) is used.
  • If target an array, target.concat(param) is used.
  • If target is null or undefined, the value is simply set.
const obj = {foo: { bar: {a:1, b:2 } };

// merge object
dotProp.merge(obj, '', {c:3} );
//=> {foo: { bar:{ a:1, b:2, c:3} } }

var arr = {foo: { bar: [1, 2] } };

// merge array
dotProp.merge(arr, '', [3, 4] );
//=> {foo: { bar:[1, 2, 3, 4 ] }