Documentation / @super-line/client

@super-line/client

The client for super-line — the strictly-typed realtime data bus for TypeScript. Call requests, listen to events, subscribe to topics, and read/write synced state — with auto-reconnect and at-most-once delivery, over a pluggable transport.

bash

pnpm add @super-line/core @super-line/client @super-line/transport-websocket zod

import { createSuperLineClient } from '@super-line/client'
import { webSocketClientTransport } from '@super-line/transport-websocket'
import { api } from './contract'

const client = createSuperLineClient(api, {
  transport: webSocketClientTransport({ url: 'ws://localhost:3000' }),
  role: 'user',
})

client.on('message', (m) => console.log(m.text))   // typed
const sub = client.subscribe('prices', (p) => render(p))
await sub.ready

const out = await client.send({ text: 'hi' })       // throws typed SuperLineError on failure
client.close()

The client is narrowed to its role's surface (shared ∪ role). The wire is carried by a pluggable transport — @super-line/transport-websocket provides the WS transport shown above; other transports (HTTP/SSE, libp2p) are available — see the Transports guide. Works in browsers and Node 22+ (pass webSocketClientTransport({ url, WebSocket }) on older runtimes).

Persisted state (collections)

Collections are typed, contract-declared state the server syncs. client.collection(name) is typed by the contract — subscribe to a live, filtered row-set, or open(id) a CRDT document whose concurrent edits merge.

import { eq } from '@super-line/core'

const messages = client.collection('messages')
const sub = messages.subscribe({ filter: eq('channelId', 'general') })
await sub.ready                        // frames process concurrently — await before depending on live delivery
sub.rows()                             // current rows
sub.subscribe((ev) => { /* { type: 'insert' | 'update' | 'delete', id, row } */ })

await messages.insert({ id: 'm2', channelId: 'general', authorId: 'me', text: 'hi', createdAt: Date.now() })

Row writes are non-optimistic — a write lands in rows() once the server confirms it; for a one-shot read without a lasting subscription, await messages.query({ filter, orderBy, limit }) resolves the snapshot and closes behind itself. For joins, live queries, and optimism, pair a collection with TanStack DB. For a collaborative document, pass crdtCollections: crdtCollectionsClient() and use client.collection(name).open(id) (getSnapshot / subscribe / update). See the Collections guide.

@super-line/client ​

Persisted state (collections) ​

Interfaces ​

Type Aliases ​

Functions ​

@super-line/client

Persisted state (collections)

Interfaces

Type Aliases

Functions