13.4.12 - race

接收并同时执行多个可观察对象，只将最快发出的数据流传递给订阅者

import { race, timer } from "rxjs"
import { mapTo } from "rxjs/operators"
const obs1 = timer(1000).pipe(mapTo("fast one"))
const obs2 = timer(3000).pipe(mapTo("medium one"))
const obs3 = timer(5000).pipe(mapTo("slow one"))
race(obs3, obs1, obs2).subscribe(console.log)