Question

这是我的代码：

＆＃13;

import {Component} from "@angular/core";
import {Subject} from "rxjs/Subject";
import {Observable} from "rxjs/Observable";
import "rxjs/add/observable/interval";
import "rxjs/add/observable/merge";
import "rxjs/add/operator/map";
import "rxjs/add/operator/startWith";
import "rxjs/add/operator/scan";
import "rxjs/add/operator/mapTo";

@Component({
  selector: 'app-root',
  template: `
    <button (click)="click$.next()">Update</button>
    <h1>{{clock | async | date:'yyyy-MM-dd HH:mm:ss'}}</h1>
  `
})
export class AppComponent {
  click$ = new Subject<any>();
  clock;

  constructor() {
    this.clock = Observable.merge(
      this.click$.mapTo('hour'),
      Observable.interval(1000).mapTo('second')
    )
      .startWith(new Date())
      .scan((acc: Date, curr) => {
        const date: Date = new Date(acc.getTime());
        if (curr === 'hour') {
          date.setHours(date.getHours() + 1);
        }
        if (curr === 'second') {
          date.setSeconds(date.getSeconds() + 1);
        }
        return date;
      });
  }
}

＆＃13;

我在startWith（新日期（））上遇到此错误，但是当我更改＆＃34; this.click $ .mapTo（＆＃39; hour＆＃39;）＆＃34 ; to＆＃34; this.click $＆＃34;，此错误消失了。任何人都可以说出了什么问题吗？

Answer 1

Observable.merge将多个可观察对象转换为单个可观察对象。当您使用以下代码时，返回类型为Observable<any,string>

  this.clock = Observable.merge(
              this.click$,
              Observable.interval(1000).mapTo('second')
            )

但是当您使用以下代码段时，返回类型为Observable<string,string>，以便scan运算符接受字符串作为第一个参数并给出错误

this.clock = Observable.merge(
      this.click$.mapTo('hour'),
      Observable.interval(1000).mapTo('second')
    )

错误TS2345：类型＆＃39;日期＆＃39;的参数不能分配给＆＃39; string |类型的参数r IScheduler＆＃39;

1 个答案: