Immutable version of dot-prop with some extensions
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Latest commit 3844f7d Nov 24, 2017
bifrost committed Nov 24, 2017 Merge pull request #19 from selfcontained/fix-default-cases
Fixes several cases around get() returning default value

dot-prop-immutable Build Status npm version

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.


var dotProp = require('dot-prop-immutable');
var 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.

var 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
var obj = {foo: {bar: 'a'}};

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

var 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

var 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

var 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.

var 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.
var 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 ] }