javascript - Why should I use immutablejs over object.freeze? -

i have researched on net benefits of immutablejs on object.freeze() didn't find satisfying!

my question why should use library , work non native data structures when can freeze plain old javascript object?

i don't think understood immutablejs offers. it's not library turns objects immutable, it's library around working immutable values.

without repeating docs , mission statement, i'll state 2 things provides:

1. types. implemented (immutable) infinite ranges, stacks, ordered sets, lists, ...

2. all of types implemented persistent data structures.

i lied, here's quote of mission statement:

immutable data cannot changed once created, leading simpler application development, no defensive copying, , enabling advanced memoization , change detection techniques simple logic. persistent data presents mutative api not update data in-place, instead yields new updated data.

i urge read articles , videos link , more persistent data structures (since they're the thing immutablejs about), i'll summarise in sentence or so:

let's imagine you're writing game , have player sits on 2d plane. here, instance, bob:

var player = {   name: 'bob',   favouritecolor: 'moldy mustard',    x: 4,   y: 10 }; 

since drank fp koolaid want freeze player (brrr! hope bob got sweater):

var player = object.freeze({     name: 'bob',     ... }); 

and enter game loop. on every tick player's position changed. can't update player object since it's frozen, copy over:

function moveplayer(player, newx, newy) {     return object.freeze(object.assign({}, player, { x: newx, y: newy })); } 

that's fine , dandy, notice how useless copying we're making: on every tick, create new object, iterate on 1 of our objects , assign new values on top of them. on every tick, on every 1 of objects. that's quite mouthful.

immutable wraps you:

var player = immutable.map({     name: 'bob',     ... });  function moveplayer(player, newx, newy) {     return player.set('x', newx).set('y', newy); } 

and through ﾉ*✧ﾟ magic ✧ﾟ*ヽ of persistent data structures promise least amount of operations possible.

there difference of mindsets. when working "a plain old [frozen] javascript object" default actions on part of everything assume mutability, , have work mile achieve meaningful immutability (that's immutability acknowledges state exists). that's part of reason freeze exists: when try otherwise, things panic. immutablejs immutability is, of course, default assumption , has nice api on top of it.

that's not all's pink , rosy cherry on top. of course, has downsides, , shouldn't cram immutable everywhere because can. sometimes, freezeing object enough. heck, of time that's more enough. it's useful library has niche, don't carried away hype.