@netless/app-embedded-page-sdk

@netless/app-embedded-page-sdk

SDK for storing shared replayable states and sending/receiving replayable events inside @netless/app-embedded-page.

中文

Install

npm add @netless/app-embedded-page-sdk

API

• createEmbeddedApp()

  Creates an embedded app instance.

  Returns: Promise<EmbeddedApp<State, Message>>

  const app = await createEmbeddedApp();
  

• app.state

  Type: State
  Default: initialState

  The synchronized state across all clients. To change it, call app.setState().

• app.page?

  Type: string

  Current whiteboard scene. It works only if scenePath has been set when calling addApp. To switch between pages, call app.setPage()

• app.isWritable

  Type: boolean

  When it is false, calling app.setState(), app.setPage(), app.sendMessage() has no effect.

• app.meta

  Type: { roomUUID?: string; userPayload?: unknown }

  Room information, including

  • roomUUID: current room's UUID.
  • userPayload: the object passed in when calling joinRoom().

• app.ensureState(partialState)

  Make sure app.state has some initial values, work as if:

  // this code won't work because app.state is readonly
  app.state = { ...partialState, ...app.state };
  

  This method modifies state locally.

  partialState

  Type: Partial<State>

  app.state; // { a: 1 }
  app.ensureState({ a: 0, b: 0 });
  app.state; // { a: 1, b: 0 }
  

• app.setState(partialState)

  Works like React's setState, it updates app.state and synchronize it to other clients.

  When some field's value is undefined, it will be removed from app.state.

  Important: Do not rely on the order of state changes:

  • app.setState() alters app.state synchronously but onStateChanged will wait until the data is successfully synced.
  • State syncing time span varies due to network status and data size. It is recommended to store only necessary data in the store.

  partialState

  Type: Partial<State>

  app.state; //=> { count: 0, a: 1 }
  app.setState({ count: app.state.count + 1, a: undefined, b: 2 });
  app.state; //=> { count: 1, b: 2 }
  

• app.setPage(page)

  Change the whiteboard scene on top of your page.

  page

  Type: string

  Important: This argument must not include /.

  app.setPage("1");
  

• app.sendMessage(message)

  Broadcast a message to other clients.

  message

  Type: anything that can be serialized in JSON.

  app.sendMessage("hello, world!");
  

• app.onStateChanged

  It fires after someone called app.setState() (including the app itself).

  Type: Emitter<{ [key: string]: { oldValue?, newValue? } }>

  app.onStateChanged.addListener(diff => {
    console.log("state changed", app.state);
  });
  

• app.onPageChanged

  It fires after someone called app.setPage() (including the app itself).

  Type: Emitter<{ oldValue?: string, newValue?: string }>

  app.onPageChanged.addListener(diff => {
    console.log("switch page to", app.page);
  });
  

• app.onWritableChanged

  It fires when app writable state changes.

  Type: Emitter<{ oldValue?: boolean, newValue?: boolean }>

  app.onWritableChanged.addListener(diff => {
    console.log("my writable becomes", app.writable);
  });
  

• app.onMessage

  It fires when receiving messages from other clients (when other clients called app.sendMessage()).

  Note: Won't receive app.sendMessage() messages sent by itself.

  Type: Emitter<any>

  app.onMessage.addListener(message => {
    console.log("received message", message);
  });
  

Example

import { createEmbeddedApp } from "@netless/app-embedded-page-sdk";

interface State {
  count: number;
}

type Message = {
  type: "click";
  payload: { id: string };
};

const app = createEmbeddedApp<State, Message>({ count: 0 });

app.state; // => { count: 0 }
app.setState({ count: 2 });
app.onStateChanged.addListener(diff => {
  if (diff.count) {
    // count: 0 -> 2
    console.log("count:", diff.count.oldValue, "->", diff.count.newValue);
    console.log(diff.count.newValue === app.state.count);
  }
});

app.sendMessage({ type: "click", payload: { id: "item1" } });
app.onMessage.addListener(({ type, payload }) => {
  if (type === "click") {
    click(payload.id);
  }
});

Licence

MIT @ netless