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Ankit Singh
Ankit Singh

Posted on • Updated on

State Management with a Single Line of Code

If you're like me and feel that there has to be an easier way of state-management, then you'd like what ActiveJS can do for you.

I feel like I'm selling snake-oil, but I spent the last 10 months trying to make state-management as intuitive and easy as possible because I couldn't stand the state-management in the state it is right now.

For efficient state-management, we need a few things

  • data structures that are type-safe
  • data structures that can emit events on mutation
  • data structures that can guarantee immutability
  • data structures that can be persisted through sessions

The title promised all this in one line of code, so here it is.

const dataUnit = new DictUnit({
 id: 'data', immutable: true, persistent: true, cacheSize: Infinity,
 initialValue: {a: 1}
})
// every option is optional, including the initialValue
// DictUnit has empty object {} as it's default value
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(Okay 4 lines, but I formatted it so you don't have to scroll :)

JavaScript doesn't have anything like that, that's why ActiveJS came into existence, and with it came reactive data structures called Units, one of them is DictUnit, that stores and ensures a dictionary object value at all times.

You might have already got a feeling from the configuration options we passed to the DictUnit and guessed what it's all about, but to elaborate DictUnit is:

  • Observable
  • Reactive
  • Type-Safe
  • Immutable
  • Persistent, and
  • Cache-Enabled

Let's see what that means in the language we all understand, the code:

Observable

DictUnit extends RxJS Observable class, so you can subscribe to it and apply all the RxJS operators on it just as you would on an Observable.

// subscribe for the value
dataUnit.subscribe(value => console.log(value))
// logs {a: 1} immediately and will log future values

dataUnit instanceof Observable; // true
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Reactive

When you update the value of a DictUnit it emits it to all the observers so that they get access to the latest value.

// non-functional dispatch
dataUnit.dispatch({b: 2, c: 3})
// observers get {b: 2, c: 3}

// now dataUnit's value is {b: 2, c: 3}

// functional-dispatch
dataUnit.dispatch(value => {return {...value, d: 4}})
// observers get {b: 2, c: 3, d: 4}

// we don't have to dispatch new values manually,
// DictUnit provides a better way to update properties

// update a single property
dataUnit.set('d', 5)
// observers get {b: 2, c: 3, d: 5}

// delete properties
dataUnit.delete('b', 'd') // 'b' and 'd' got yeeted
// observers get {c: 3}

// update multiple properties
dataUnit.assign({a: 1, b: 2})
// observers get {a: 1, b: 2, c: 3}
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Type-Safe

A DictUnit ensures that at all times the value is always a dictionary object, it'll ignore any invalid value dispatch.

dataUnit.dispatch(['let', 'me', 'in']); // won't work
dataUnit.dispatch('let me in'); // won't work
dataUnit.dispatch(420); // won't work
dataUnit.dispatch(null); // won't work
dataUnit.dispatch(new Date()); // won't work
dataUnit.dispatch(() => new Date()); // won't work
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There are 5 other Units just like DictUnit in ActiveJS, ListUnit to store array, NumUnit to store number, StringUnit to store string, BoolUnit to store boolean, and GenericUnit to store anything.

Immutable

The immutable flag makes sure that the DictUnit doesn't let the value get mutated in any way. Let's try to mutate it anyway.

const newValue = {c: 3};
dataUnit.dispatch(newValue) // works, value is {c: 3} now

// try mutating the newValue
newValue.c = 'hehe' // works, but
dataUnit.value() // still {c: 3}

// let's try a different approach
const currentValue = dataUnit.value() // {c: 3}
currentValue.c = 'gotcha' // works, but
dataUnit.value() // still {c: 3}
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Persistent

The persistent flag makes the DictUnit persistent, such that whenever its value is updated, it saves that value to LocalStorage, so if we reinitialize a DictUnit with the same id and persistent: true flag, the DictUnit will restore its value from LocalStorage.

dataUnit.dispatch({c: 4}) // saved in LocalStorage

// after refreshing the browser-tab or reinitializing the DictUnit
dataUnit.value() // {c: 4}
// it restored the value from LocalStorage
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Cache-Enabled

What if I told you that we can go back to all the previous values we just updated in previous examples, and then come back to the current value, yup Time-Travel is possible. All you need to provide is how many steps you want to be able to go back using the cacheSize option, by default it keeps 2 values and supports up to Infinity.

// let's reinitialize the Unit to demonstrate cache-navigation
const dataUnit = new DictUnit({
 cacheSize: Infinity, initialValue: {a: 1}
})
// now let's dispatch a bunch of values to fill the cache
dataUnit.dispatch({b: 2})
dataUnit.dispatch({c: 3})
dataUnit.dispatch({d: 4})
dataUnit.dispatch({e: 5})

// now the value is {e: 5}, and
// the cache looks like this [{a: 1}, {b: 2}, {c: 3}, {d: 4}, {e: 5}]

// go back 1 step
dataUnit.goBack()
// now value is {d: 4}

// go back 2 steps
dataUnit.jump(-2) // negative means back, positive means forward
// now value is {b: 2}

// jump to the last value in cache
dataUnit.jumpToEnd()
// now value is {e: 5}

// jump to the first value in cache
dataUnit.jumpToStart()
// now value is {a: 1}

// go forward 1 step
dataUnit.goForward()
// now value is {b: 2}
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That's it, folks, all done.

There are still a few things that we haven't covered that DictUnit can do, and we also haven't covered things like managing asynchronous API calls. But maybe that's a topic for the next article.

In the meantime, stay safe, try to have fun, and head over to ActiveJS website or documentation to learn more about how it can help you manage state with minimum effort.

Here's the StackBlitz playground link if you want to try it out yourself.

Here's a link to the visual playground, which you can try out without writing any code.

Also, I forgot to tell you that this is my first ever article on any platform, please let me know if I did an okay job, or if there's something that I can improve.

Cheers

🌏 ActiveJS Website
📖 ActiveJS Documentation
🤾‍♂️ ActiveJS Playground
💻 ActiveJS GitHub Repo (drop a ⭐ maybe :)

Next Read: Asynchronous State Management with ActiveJS

Discussion (46)

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zalithka profile image
Andre Greeff

Careful Ankit, you might just make people actually start enjoying state management if you carry on like this.. (:

All jokes aside, this is a very nicely written article though, thanks for the ActiveJS intro! :D

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dabalyan profile image
Ankit Singh Author

Hey Andre, wouldn't that be something ;)

thank you :)
I'm just glad that I didn't mess up

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avkonst profile image
Andrey

Have a look into Hookstate hookstate.js.org. it is truly one line state management, but covers a lot of use cases and takes care of rerendering performance without extra effort from a programmer

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robvirtuoso profile image
robvirtuoso • Edited on

I'm just keeping track of how this guy shamelessly plugs his HookState library seemingly everywhere. Promoting it is quite ok, but comparing it this way is not... I mean, does it have to be a competition who has the best library??? I find this self-promotion quite distasteful.

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avkonst profile image
Andrey

Could you please do a favor for everybody on the internet and educate all others, who post comments pointing out to alternatives?

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robvirtuoso profile image
robvirtuoso • Edited on

That would be easy because not a lot of them point to their OWN library as the "alternative". And much less would blatantly even imply that their library is the better one.

Your library is not bad at all, so just be careful not to leave a bad taste in people's mouths with your posts. It won't be doing your library any favor.

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avkonst profile image
Andrey

At least I am honest and publish it from my own single account and put a disclaimer. It would be quite naive to believe that "promotions" (not only about this category of libs) are done by other independent people if they are not done from "an owner's account".

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robvirtuoso profile image
robvirtuoso • Edited on

I'm not trying to antagonize you. I just hate the idea that independent open source contributors like you will get a bad reputation due to their posts like this. I find publishing open source libs a noble thing to do, especially for people who don't earn a dime from it. You seem like you belong to this category, so I appreciate your efforts. I actually help promote work of libs that I personally use, as a way of giving back to the author/maintainer. If your posts triggered a bad reaction from me, it may happen with others too. So again I wouldn't wish you that misfortune.

You may not be asking for advice from me, but if it was me I would not want people thinking that I'm doing this to compete with the big guys (Redux, Recoil, etc.) which are backed by a big corporation and fanboys... And nor would I ever say that my lib is superior to another , popular or new one.... open source is not a popularity contest after all. As long as a number of people actually use your library, i.e. it is helping some folks out there, it means you already are doing a good job.

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dabalyan profile image
Ankit Singh Author

hey Andrey, kudos for the amazing things you're doing with hookstate.

I remember stumbling on hookstate at some time when I was searching for alternatives to reducer based state managers, I really liked the hookstate. But as I don't have much experience or use case for React, I had to move on. I guess that's one of the differences that sets ActiveJS apart, it can be used with any framework, or even without a framework as well.

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darlantc profile image
Darlan Tódero ten Caten

Your first article is just... awesome! Well done man!

About your library, I'm very impressed with so much love you put into it: beautiful website, incredible documentation with examples to easily verify how it works.

I'm very happy with MobX at the moment in my projects but I certainly will try your library in future projects as I really love how simple it is.

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dabalyan profile image
Ankit Singh Author

thank you :)

I didn't have much else to do, but still it wasn't easy, thanks for noticing :)

Making it simple was the objective, "Pragmatic not Idealistic" is the motto.
Glad that you find it that way :)

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rschneider94 profile image
Rodrigo Schneider

Hey Ankit! Really nice article, thanks for sharing this! Wish I knew this a few months ago.

Just a little correction: in the Type-Safe heading you typed disptach instead of dispatch. It's not a big deal, but just to let you know in case you didn't notice that.

Have a great day and I'm already following you! :)

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dabalyan profile image
Ankit Singh Author

hey Rodrigo,
my pleasure, and I wish could have finished it sooner :)

damn, didn't know I was dyslexic, thanks for letting me know, jk ;)
fixed it

you too, thank you :)

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fly profile image
joon • Edited on

So yesterday I was feeling fed up with setting up redux and realizing
that the whole process was going to be a pain when I just needed simple
global state functionality.
Instead of the obvious 'searching for a good alternative' I just went and wrote a single file version instead.

gist.github.com/fl-y/dc500f0841fd1...

Quite pleased with myself,
on my way to work while scrolling through dev.to I noticed this gem.
I feel like this is pretty much what my prototype would have become with a LOT of hard work(But probably multitudes worse).
I sincerely thank you for sharing this project.

Going to try this out straight away :)

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pclundaahl profile image
Patrick Charles-Lundaahl

Adding on to my last comment, I'd just like to say that, while I may not may not use this myself (I only really do front-end development at work, and that's almost exclusively limited to modifying existing apps), I think this is just a really cool project.

Regardless of current bundle size, etc., having more people thinking about state management and trying to improve it just strikes me as a really good thing.

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dabalyan profile image
Ankit Singh Author

It's okay if you can't use it, the encouraging words are good enough :)

Regarding the bundle size, I guess there's some confusion, the 8kB is the complete library bundled together (without tree-shaking) along with RxJS dependencies. If you're using a module bundler or already using RxJS in your project, the final build size contribution will be much lower.

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kgignatyev profile image
Konstantin Ignatyev

Interesting idea, but 'working' assignments which do nothing is very bad idea.

newValue.c = 'hehe' // works, but

dataUnit.value() // still {c: 3}

that is not acceptable IMO, must throw exception

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dabalyan profile image
Ankit Singh Author

thanks :)

There's an option to enable that behavior as well, but it's only recommended to be used in development mode, see checkImmutability flag in docs.activejs.dev/guides/developme...

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kgignatyev profile image
Konstantin Ignatyev

Well, I think that should be the only behavior.

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dabalyan profile image
Ankit Singh Author

ActiveJS is configured with most sensible defaults, and gives you the ability to configure it in your own way.

You can keep the checkImmutability check on in the production as well, but it's not something that ActiveJS or people much smarter than me recommend :)

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inlagny profile image
MadeInLagny

Nice work ! Since you subscribe to variables and not store, how do you deal with this in a component-based app ? Do you need to susbscribe to all required values in each component ?

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dabalyan profile image
Ankit Singh Author • Edited on

hey MadeInLagny, thanks :)

The general idea is that you access the Units directly, wherever required, however if two Units make more sense together, you can keep them separate but get their combined value by grouping them together using a Cluster.

// two Units
export const unit1 = new DictUnit({initialValue: {a: 1}});
export const unit2 = new DictUnit({initialValue: {b: 2}});
// grouped together
export const myGroup = new Cluster({unit1, unit2}) // using shorthand notation
// subscribe for reactive grouped value access
myGroup.subscribe(groupedValue => console.log(groupedValue))
// you'll see {unit1: {a: 1}, unit2: {b: 2}} in the console immediately and 
// it'll also log any future values
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inlagny profile image
MadeInLagny

But how do you access myGroup value in a component where it was not initialised ?

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dabalyan profile image
Ankit Singh Author • Edited on

ahh I see, do you mean how to share a Unit or Cluster with multiple components?

you initialize them and export them from a separate file, then you can access them wherever needed, with a simple/direct import.

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tojacob profile image
Jacob Samuel G.

I love that you use rxjs. I was going to write something similar (not so good) for my next project. It may be irrelevant, but what happens when LocalStorage is not available? Personally I use "Persistore" to handle storage, as I am confident in the falls back it offers. I haven't checked the Active source code yet. Do you think it could support plugins to handle persistence?

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dabalyan profile image
Ankit Singh Author • Edited on

thanks :)

are you referring to usage in NodeJS environment? Because all modern browsers have localStorage afaik. And if it's not available then plugins won't be able to help there.

that being said, yes you can replace the storage used for persistence, anything that implements the Storage developer.mozilla.org/en-US/docs/W... interface can be used, see docs.activejs.dev/guides/persistence.

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jonrandy profile image
Jon Randy

One line... plus 1.64MB to import the library, and likely add dependencies on top of that. Ludicrous

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dabalyan profile image
Ankit Singh Author

only 8kB gzipped, and it's tree-shakeable too, that's what would go to production, not all the 1.64MBs of documentation, typings, and unpacked code.

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aisone profile image
Aaron Gong

Thank you for the good effort.

Yes it is 8KB gzip, will also need to add 11kb for rxjs (but this is ok for those who have use case for rxjs).

The next step is to make the library have as little dependencies as possible. One that does not have breaking changes or at least are easily manageable.

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dabalyan profile image
Ankit Singh Author

my pleasure :)

not quite correct, those 8kBs include all the RxJS dependencies that ActiveJS has, and 8kBs are for projects that are going to use ActiveJS without a module bundler, the target use case of ActiveJS is going to be modern Web-Apps built with modern frameworks, all of them have a module bundler like webpack, to eliminate any unused/dead-code from the bundle, see en.wikipedia.org/wiki/Tree_shaking.

Dependency on RxJS is a feature not a bug ;)
Since the ActiveJS Units extend RxJS' Observable class, it gives you the possibility to use all the myriads of RxJS operators.

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darlantc profile image
Darlan Tódero ten Caten

Why so angry man? You just read the title and get straight here to comment without taking the time to analyze the work of the author?

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ckapilla profile image
Chris Kapilla

very impressive design -- I will investigate it further.

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pclundaahl profile image
Patrick Charles-Lundaahl

That's one heck of a first article! Bravo!

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dabalyan profile image
Ankit Singh Author

this means a lot, thank you :)

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damianesteban profile image
Damian Esteban

This is an impressive library. Thanks for the share :).

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anuraghazra profile image
Anurag Hazra

This looks promising

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shirkan profile image
Liran Cohen

Well done

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zoedreams profile image
☮️✝️☪️🕉☸️✡️☯️

nice article. i like the type checking ability. A sneaky way to use strong typing. Thank you for sharing

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emex4gman profile image
Ibebugwu Chukwuemeka

This is real nice. Probably try it out in my next project

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srikanth597 profile image
srikanth597

Interesting, glad I found this.

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yurieastwood profile image
Yuri Eastwood

Woah, nice article! I was even more astonished when I read was your first! hehe
Didn't knew about ActiveJS, it seems really interesting!

Keep up the good work! Kudos!

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jvas28 profile image
Julio Vasconez Yulan

Amazing work man!

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dabalyan profile image
Ankit Singh Author

hey Julio, what a surprise, great to see you here :)

thanks :)

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hakimio profile image
Tomas Rimkus

Why not just use Akita? It's really simple and works well with vanilla JS -> datorama.github.io/akita/docs/addi...

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kashkovsky profile image
Denis Kashkovsky

What about github.com/grammarly/focal ? In addiction Focal can lift any react component to receive props as observables.

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dabalyan profile image
Ankit Singh Author

Never heard about it, just checked it out, "focal" looks great, it's a very similar approach I must say. From what I could gather, it only works with React, ActiveJS has no such affiliation as of yet, that can be a good or bad thing depending on who you ask. We don't have any plans to create special bindings for any framework, but it's something that we can think about. Thanks for sharing this.