Ionic4—简单的超时设置

import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { TimeoutError } from 'rxjs';
import { timeout }  from 'rxjs/operators';

...

constructor(public http: HttpClient) { }

...

dourl() {
    var api = '';
    this.http.get(api).pipe(timeout(3000)).subscribe((response) => {
        console.log(response);
    }, (err) => {
        if (err instanceof TimeoutError) {
            console.log('服务器连接超时');
        } else if (err instanceof HttpErrorResponse) {
            console.log('网络连接异常');
        } else {
            console.log('未知原因，请求失败');
        }
    });   
}