RxJS - 釋出行為運算子 publishBehavior

publishBehaviour 使用 BehaviourSubject，並返回 ConnectableObservable。connect() 方法必須用於訂閱建立的可觀察物件。

語法

publishBehaviour(defaultvalue)

示例

import { interval} from 'rxjs';
import { take, publishBehavior} from 'rxjs/operators';

let observer = interval(1000).pipe(
   take(5),
   publishBehavior(4)
);
const subscribe_one = observer.subscribe(
   x => console.log("Value from Sub1 = "+x)
);
const subscribe_two = observer.subscribe(
   x => console.log("Value from Sub2 = "+x)
);
observer.connect();
console.log("After 2 seconds");
setTimeout(() => {
   const subscribe_three = observer.subscribe(
      x => console.log("Value from Sub3 = "+x)
   );
}, 2000);

輸出

首先會顯示預設值，然後顯示來自可觀察物件的值。