immutable
Advanced tools
Package description
The immutable npm package provides persistent immutable data structures that do not change once created, enabling advanced memoization, change detection, and functional programming techniques. It offers a variety of data structures such as List, Map, Set, and Record.
Persistent Immutable List
Create and manipulate immutable lists, where modifications return new lists without altering the original.
const { List } = require('immutable');
const list1 = List([1, 2, 3]);
const list2 = list1.push(4);
console.log(list1.size); // 3
console.log(list2.size); // 4Persistent Immutable Map
Create and manipulate immutable maps, with key-value pairs. Changes produce new maps without changing the original.
const { Map } = require('immutable');
const map1 = Map({ a: 1, b: 2, c: 3 });
const map2 = map1.set('b', 50);
console.log(map1.get('b')); // 2
console.log(map2.get('b')); // 50Persistent Immutable Set
Create and manipulate immutable sets, which are collections of unique values. Adding existing values does not change the set.
const { Set } = require('immutable');
const set1 = Set([1, 2, 3]);
const set2 = set1.add(3).add(4);
console.log(set1.has(3)); // true
console.log(set2.has(4)); // trueRecord Factory
Define 'Record' factories to create immutable records with default values and specific shapes.
const { Record } = require('immutable');
const Person = Record({ name: null, age: null });
const person1 = new Person({ name: 'Alice', age: 30 });
const person2 = person1.set('name', 'Bob');
console.log(person1.name); // Alice
console.log(person2.name); // BobMori is a library that provides immutable data structures and functional programming utilities. It is similar to immutable but wraps the ClojureScript's data structures and has a different API.
Immer offers a different approach to immutable data. Instead of persistent data structures, it allows you to work with the standard JavaScript data structures in an immutable way by using a draft state and producing the next immutable state.
Seamless-immutable provides immutability for arrays and objects without introducing new data structures. It is simpler and has a smaller API surface compared to immutable, but it does not offer the same level of functional programming support.
Readme
Effecient immutable data-structures in javascript.
Mutability causes headaches; immutability soothes them. JavaScript's Object and Array are crying out for immutable counterparts to complement first-class functions.
var im = require('immutable')
var person = im.object({ firstName: 'hugh', secondName: 'jackson' })
var personWithAge = person.assoc({ age: 24 })
person.has('age') //= false
personWithAge.has('age') //= true
personWithAge.get('age') //= 24
npm install immutable
Create an empty immutable object:
var o = im.object()
Or define the initial set of properties:
var you = im.object({ wise: true, willUseThisLib: true })
Create a new immutable object with a property added or updated:
var emptyObject = im.object()
var basicPerson = o.assoc('human', true)
Or pass an object to define multiple properties at once:
var personRecord = basicPerson.assoc({ name: 'joe bloggs', age: 34 })
Get a property:
var person = im.object({ name: 'joe bloggs', age: 34 })
person.get('age') //= 34
It works on numeric keys too, although you're more likely to use an array for this:
var readingList = im.object({ 1: 'Operating System Design: The Xinu Approach' })
readingList.get(1) //= 'Operating System Design: The Xinu Approach'
Check if an immutable object has a property:
var person = im.object({ name: 'joe bloggs', age: 34 })
person.has('name') //= true
person.has('discography') //= false
Create a new immutable object without a property:
var person = im.object({ name: 'joe bloggs', age: 34 })
var personShyAboutAge = person.dissoc('age')
personShyAboutAge.get('age') //= undefined
Create a regular JavaScript object from an immutable one:
var person = im.object({ name: 'joe bloggs', age: 34 })
person.mutable() //= { name: 'joe bloggs', age: 34 }
The .toJSON alias allows immutable objects to be serialised seamlessly with regular objects:
var favouritePeople = {
joe: im.object({ name: 'joe bloggs', age: 34 })
}
var data = JSON.stringify(favouritePeople)
data // = { joe: { name: 'joe bloggs', age: 34 } }
Create a new immutable array:
var arr = im.array()
or with initial values:
var arr = im.array([1, 2, 3, 4])
Work identically in imutable.array as they do in immutable.object, except that they keep the .length property of the array up to date.
Check the 'length' of an immutable array:
var arr = im.array([1, 2, 3])
arr.length //= 3
Create a regular JavaScript object from an immutable one:
var todo = im.array(['write README', 'run tests on all supported platform'])
todo.mutable() //= ['write README', 'run tests on all supported platform']
The .toJSON alias allows immutable objects to be serialised seamlessly with regular objects:
var lists = {
todo: im.array(['write README', 'run tests on all supported platform'])
}
var data = JSON.stringify(lists)
data // = { todo: ['write README', 'run tests on all supported platform'] }
FAQs
Immutable Data Collections
We found that immutable demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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