immutable concepts

gistfile1.txt

Immutable data and Immutable.js
Inspired by Clojure, Scala, Haskell

Persistent data means API yields new updated data.

Data structures include: List, Stack, Map, OrderedMap, Set, OrderedSet, Record

Efficiency through use of structural sharing via hash map tries and vector tries.

npm install immutable
or
<script src="immutable.min.js"></script>

Data is passed from above rather than subscribed to.
Immutable collections treated as values rather than objects. 
Values represent state at particular instance of time.
Objects are "copied" by making reference to original,
enable memory savings and speed boost.

API that returns new immutable collections
Array is to Immutable.List
Map is to Immutable.Map
Set is to Immutable.Set
Accepts raw JS objects, expects an Iterable
Seq evaluates lazily and does not cache immediate results
Immutable.Map accepts keys of any type
JavaScript Object properties are always strings

Converts back to raw JS objects shallowly with:
toArray(), toObject(), toJS(), toJSON()

Nested Structures
deep trees of data
mergeDeep(), updateIn(), getIn(), setIn()

Lazy Seq: lazy op for efficient chaining of iterable methods
assigning to variable does not execute
only performs work enough for requested result
take(), get()

Equality
=== and !=== checks instances
is() and equals() checks equivalent values

Batching Mutations
apply series of mutations before returning
creates temporary mutable copy of collection
withMutations(), asMutable(), asImmutable()