stx

A blazing fast state manager with network sync out of the box.

• Set and get deep nested paths
• Data listeners for watching changes
• Subscriptions for watching deep nested changes
• In-state references with special notation
• Create branches from a master state
• Minimum state diff is synchronised over web sockets
• Works both on server and browser

Here is a fully working Vue example

Here is the complete documentation (WIP)

Here is a persistency plugin for RocksDB

Qucik Start Guide

CRUD operations

Create

const { create } = require('stx')
const state = create({ firstKey: 'value' })

Serialize

state.serialize() // → { firstKey: 'value' }

Set

⚠ Default behaviour is merge.

state.set({ second: { subKey: 'subValue' } })
state.serialize() // → { firstKey: 'value', second: { subKey: 'subValue' } }

Get

state.get('second').serialize() // → { subKey: 'subValue' }

Remove

state.set({ firstKey: null })
state.get('firstKey') // → undefined
state.serialize() // → { second: { subKey: 'subValue' } }

Compute

⚠ Paths are represented as arrays for nested keys.

const subKey = state.get(['second', 'subKey'])
subKey.compute() // → subValue

Get with set

Second parameter of get is a default value for the path.

⚠ It will be set and returned if the relative path is undefined, otherwise it will be ignored.

state.get('first', 1).compute() // → 1
state.get('first').compute() // → 1

Navigate

Path

subKey.path() // → [ 'second', 'subKey' ]

Parent

subKey.parent().serialize() // → { subKey: 'subValue' }

Root

subKey.root().serialize() // → { second: { subKey: 'subValue' }, first: 1 }

Listeners

On

⚠ A listener without a name is by default a data listener. Fires on set, remove, add-key, remove-key.

let fired = []
state.set({ third: 3 })
const third = state.get('third')
const listener = third.on((val, stamp, item) => fired.push(`${val}-${item.compute()}`))
fired // → []
third.set('changed')
fired // → [ 'set-changed' ]
state.set({ third: 'again' })
fired // → [ 'set-changed', 'set-again' ]

Off

listener.off()
third.set('yet again')
fired // → [ 'set-changed', 'set-again' ]

Emit

⚠ Events fired on a path can be listened only at exact same path.

const errors = []
state.on('error', err => errors.push(err))
state.emit('error', 'satellites are not aligned')
errors // → [ 'satellites are not aligned' ]
subKey.on('error', err => errors.push(err))
subKey.emit('error', 'splines are not reticulated')
errors // → [ 'satellites are not aligned', 'splines are not reticulated' ]

Creating branches from master state

const master = create({
  movies: {
    runLolaRun: {
     year: 1998,
     imdb: 7.7,
     title: 'Run Lola Run'
    },
    goodByeLenin: {
      year: 2003,
      imdb: 7.7,
      title: 'Good Bye Lenin'
    },
    theEdukators: {
      year: 2004,
      imdb: 7.5,
      title: 'The Edukators'
    }
  }
})
 
const branchA = master.create({
  userName:'A',
  movies: {
    runLolaRun: { favourite: true },
    theEdukators: { favourite: true }
  }
})
 
const branchB = master.create({
  userName:'B',
  movies: {
    goodByeLenin: { favourite: true }
  }
})
 
master.get('userName') // → undefined
 
branchA.get(['movies', 'theEdukators']).serialize()
// → { favourite: true, year: 2004, imdb: 7.5, title: 'The Edukators' }
branchB.get(['movies', 'theEdukators']).serialize()
// → { year: 2004, imdb: 7.5, title: 'The Edukators' }
master.get(['movies', 'theEdukators']).serialize()
// → { year: 2004, imdb: 7.5, title: 'The Edukators' }
 
master.get(['movies', 'runLolaRun', 'rating'], 'R')
branchB.get(['movies', 'runLolaRun', 'rating']).compute() // → R
branchA.get(['movies', 'runLolaRun', 'rating']).compute() // → R
 
branchB.get(['movies', 'runLolaRun', 'rating']).set('G')
branchA.get(['movies', 'runLolaRun', 'rating']).compute() // → R
 
master.get(['movies', 'runLolaRun', 'rating']).set('PG')
branchA.get(['movies', 'runLolaRun', 'rating']).compute() // → PG
branchB.get(['movies', 'runLolaRun', 'rating']).compute() // → G

Listeners on branches

⚠ Events fired on master can be listened on branches and branches of branches.

fired = []
branchA.get('movies').on('reload', val => fired.push(`A-${val}`))
branchB.get('movies').on('reload', val => fired.push(`B-${val}`))
master.get('movies').emit('reload', 'now')
branchA.get('movies').emit('reload', 'later')
fired // → [ 'A-now', 'B-now', 'A-later' ]

References

branchB.set({
  watched: {
    runLolaRun: [ '@', 'movies', 'runLolaRun' ],
    goodByeLenin: [ '@', 'movies', 'goodByeLenin' ]
  } 
})
 
branchB.get([ 'watched', 'goodByeLenin', 'favourite' ]).compute() // → true
branchB.get([ 'watched', 'runLolaRun', 'favourite' ]) // → undefined

Origin

branchB.get([ 'watched', 'goodByeLenin' ]).serialize()
// → [ '@', 'movies', 'goodByeLenin' ]
branchB.get([ 'watched', 'goodByeLenin' ]).origin().serialize()
// → { favourite: true, year: 2003, imdb: 7.7, title: 'Good Bye Lenin' }

Data listeners on references

⚠ It is also possible to listen data events explicitly.

fired = []
branchB.get([ 'watched', 'runLolaRun' ])
  .on('data', (val, stamp, item) => {
    fired.push(`${val}-${item.get('favourite').compute()}`)
  })
branchB.get([ 'movies', 'runLolaRun' ]).set({ favourite: true })
fired // → [ 'add-key-true' ]

Subscriptions

let count = 0
const items = create({
  i1: {
    title: 'Item 1',
    items: {
      sub2: ['@', 'i2'],
      sub3: ['@', 'i3']
    }
  },
  i2: {
    title: 'Item2',
    items: {
      sub1: ['@', 'i1']
    }
  },
  i3: {
    title: 'Item3',
    items: {
      sub2: ['@', 'i2']
    }
  }
})
 
let subscription = items.get('i2').subscribe(() => { count++ })
count // → 1 (fired once for existing path)
 
items.set({
  i2: {
    title: 'Title2'
  }
})
count // → 2 (fired once more for immediate child)
 
items.get('i3').set({
  title: 'Title3'
})
count // → 3 (fired once more for nested child)
// i2.items.sub1.items.sub3.title === i3.title
 
subscription.unsubscribe()

Subscription options

count = 0
subscription = items.get('i2').subscribe({
  keys: [ 'items' ],
  depth: 3
}, () => { count++ })
count // → 1 (fired once for existing path)
 
items.set({
  i2: {
    title: 'Title2'
  }
})
count // → 1 (did not fire for ignored key)
 
items.get('i1').set({
  title: 'Title1'
})
count // → 2 (fired once more for 3rd level depth nested)
 
items.get('i3').set({
  description: 'Description3'
})
count // → 2 (did not fire for more than 3rd level depth)
 
subscription.unsubscribe()

Over the wire

Server

const server = items.listen(7171)
items.on('log', line => {
  line // → Hello!
  server.close()
})

Client

const cItems = create()
const client = cItems.connect('ws://localhost:7171')
cItems.get('i1', {}).subscribe(
  { depth: 1 },
  i1 => {
    if (i1.get('title')) {
      cItems.serialize() // → { i1: { title: 'Title1', items: {} } }
      cItems.emit('log', 'Hello!')
      client.socket.close()
    }
  }
)