13.5.3 - pluck

获取数据流对象中的属性值

import { interval } from "rxjs"
import { pluck, mapTo } from "rxjs/operators"
interval(1000)
  .pipe(
      mapTo({ name: "张三", a: { b: "c" } }), 
      pluck("a", "b")
    )
.subscribe(n => console.log(n))