dot-prop-immutable

Immutable version of dot-prop with some extensions.

1npm 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:

1get(object, path) --> value
2set(object, path, value) --> object
3delete(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.

Usage

1const dotProp = require('dot-prop-immutable');
2let state = { todos: [] }, index = 0;
3
4// Add todo:
5state = dotProp.set(state, 'todos', list => [...list, {text: 'cleanup', complete: false}])
6// or with destructuring assignment
7state = {...state, todos: [...state.todos, {text: 'cleanup', complete: false}]};
8//=>  { todos: [{text: 'cleanup', complete: false}] }
9
10// Complete todo:
11state = dotProp.set(state, `todos.${index}.complete`, true)
12// or with destructuring assignment
13state = {...state, todos: [
14	...state.todos.slice(0, index),
15	{...state.todos[index], complete: true},
16	...state.todos.slice(index + 1)
17]};
18//=>  { todos: [{text: 'cleanup', complete: true}] }
19
20// Delete todo:
21state = dotProp.delete(state, `todos.${index}`)
22// or with destructuring assignment
23state = {...state, todos: [
24	...state.todos.slice(0, index),
25	...state.todos.slice(index + 1)
26]};
27//=>  { todos: [] }

get

Access a nested property by a dot path

1// Getter
2dotProp.get({foo: {bar: 'unicorn'}}, 'foo.bar')
3//=> 'unicorn'
4
5dotProp.get({foo: {bar: 'a'}}, 'foo.notDefined.deep')
6//=> undefined
7
8dotProp.get({foo: {bar: 'a'}}, 'foo.notDefined.deep', 'default value')
9//=> default value
10
11dotProp.get({foo: {'dot.dot': 'unicorn'}}, 'foo.dot\\.dot')
12//=> 'unicorn'

or use a property array as a path.

1// Use an array as get path
2dotProp.get({foo: {'dot.dot': 'unicorn'}}, ['foo', 'dot.dot'])
3//=> 'unicorn'

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

1const obj = {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn']};
2
3// Index into array
4dotProp.get(obj, 'foo.1')
5//=> 'white-unicorn'
6
7dotProp.get(obj, 'foo.0.bar')
8//=> 'gold-unicorn'
9
10// Index into array with $end
11dotProp.get(obj, 'foo.$end')
12//=> 'silver-unicorn'
13
14// If obj is an array
15dotProp.get([{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn'], '0.bar')
16//=> 'gold-unicorn'
17

set

Modify a nested property by a dot path

1// Setter
2const obj = {foo: {bar: 'a'}};
3
4const obj1 = dotProp.set(obj, 'foo.bar', 'b');
5//obj1 => {foo: {bar: 'b'}}
6
7const obj2 = dotProp.set(obj1 , 'foo.baz', 'x');
8//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.

1// Setter where value is a function (get and set current value)
2dotProp.set({foo: {bar: 'a'}}, 'foo.bar', v => v + 'bc')
3//=> {foo: {bar: 'abc'}}

Modify a nested array

1const obj = {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn']};
2
3// Index into array
4dotProp.set(obj, 'foo.1', 'platin-unicorn')
5//=> {foo: [{bar: 'gold-unicorn'}, 'platin-unicorn', 'silver-unicorn']}
6
7dotProp.set(obj, 'foo.0.bar', 'platin-unicorn')
8//=> {foo: [{bar: 'platin-unicorn'}, 'white-unicorn', 'silver-unicorn']}
9
10// Index into array with $end
11dotProp.set(obj, 'foo.$end', 'platin-unicorn')
12//=> {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'platin-unicorn']}
13

delete

Delete a nested property/array by a dot path

1const obj = {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn', 'silver-unicorn']};
2
3// delete
4dotProp.delete(obj, 'foo.$end');
5//=> {foo: [{ bar: 'gold-unicorn'}, 'white-unicorn']}
6
7dotProp.delete(obj, 'foo.0.bar');
8//=> {foo: [{}, 'white-unicorn', 'silver-unicorn']}

toggle

Toggle a boolean a value by a dot path.

1const obj = {foo: { bar: true } };
2
3// toggle
4dotProp.toggle(obj, 'foo.bar');
5//=> {foo: { bar: false } }

merge

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.

1const obj = {foo: { bar: {a:1, b:2 } };
2
3// merge object
4dotProp.merge(obj, 'foo.bar', {c:3} );
5//=> {foo: { bar:{ a:1, b:2, c:3} } }
6
7var arr = {foo: { bar: [1, 2] } };
8
9// merge array
10dotProp.merge(arr, 'foo.bar', [3, 4] );
11//=> {foo: { bar:[1, 2, 3, 4 ] }

License

MIT