Question

publish

函数签名: publish() : ConnectableObservable

共享源 observable 并通过调用 connect 方法使其变成热的。

示例

示例 1: 在订阅之后调用 observable 的 connect 方法

( StackBlitz | jsBin | jsFiddle )

// RxJS v6+
import { interval } from 'rxjs';
import { publish, tap } from 'rxjs/operators';

// 每1秒发出值
const source = interval(1000);
const example = source.pipe(
  // 副作用只会执行1次
  tap(_ => console.log('Do Something!')),
  // 不会做任何事直到 connect() 被调用
  publish()
);

/*
  source 不会发出任何值直到 connect() 被调用
  输出: (5秒后)
  "Do Something!"
  "Subscriber One: 0"
  "Subscriber Two: 0"
  "Do Something!"
  "Subscriber One: 1"
  "Subscriber Two: 1"
*/
const subscribe = example.subscribe(val =>
  console.log(`Subscriber One: ${val}`)
);
const subscribeTwo = example.subscribe(val =>
  console.log(`Subscriber Two: ${val}`)
);

// 5秒后调用 connect，这会使得 source 开始发出值
setTimeout(() => {
  example.connect();
}, 5000);

其他资源

• publish :newspaper: - 官方文档

源码: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/publish.ts