WebSocket (to way connection)

used for: chats, live data, games, trading dashboards, notifications, monitoring, etc.

onopen - init
onmessage - get messages
send
onerror - error handling
onclose

fetch + ReadableStream (one-way streaming)

used for: AI models (OpenAI, Claude), large CSV/logs, video/audio streams, ect.

 { stream: true } - Request-side configuration, sends the answer by chunks

 response.body.getReader() - ReadablStream, get data step by step

ReadableStream

find Claude \ OpenAI base integrations in lib folder