Collector

The Collector reconstructs the assembled object from patches. Runs on your client. Transport-agnostic — feed it patches from SSE, WebSocket, or any source.

Constructor

import { Collector } from 'jsoncurrent'
 
const collector = new Collector<T>()

The type parameter T is the expected shape of the fully assembled object.

Properties

collector.value

The current partially-assembled state. Updates after every data patch.

console.log(collector.value) // Partial<T>

Methods

collector.consume(chunk)

Feed a deserialised StreamingChunk patch. Call this for each message from your transport.

source.onmessage = (event) => {
  collector.consume(JSON.parse(event.data)) // ← deserialise first
}

collector.complete()

Signal end of stream. Fires the complete event with the fully assembled object.

collector.complete()

collector.reset()

Reset state and seen paths. Preserves middleware and event listeners. Returns this.

collector.reset()

collector.use(fn)

Register a middleware function. Returns this for chaining.

collector.use((patch, next) => {
  next(patch)
})

Events

change

Fires on every data patch (add, append, insert) with the current partial state.

collector.on('change', (state: Partial<T>) => {
  setData(state)
})

complete

Fires once when complete() is called with the fully assembled object.

collector.on('complete', (final: T) => {
  save(final)
})

pathstart

Fires the first time a path receives a data patch within this stream. value is the initial type — {} for objects, [] for arrays, or the first string chunk. Resets on reset().

collector.on('pathstart', (path: string, value: unknown) => {
  if (/^sections\[\d+\]$/.test(path)) showSkeleton(path)
})

pathcomplete

Fires when a value at a path is fully assembled. value is a deep-snapshotted copy of the assembled value — safe to store and render.

collector.on('pathcomplete', (path: string, value: unknown) => {
  if (/^sections\[\d+\]$/.test(path)) replaceSkeleton(path, value)
})

error

Fires when an unknown op or malformed patch is consumed.

collector.on('error', (err: JsonCurrentError) => {
  console.error('Collector error', err)
})