angular - 发送消息或在angular2中打开消息后，如何使页面自动向下滚动到底部

Question

我有一个消息对话部分，在其中我需要将滚动条显示在底部，并且当页面再次打开时，滚动条必须在底部。我的意思是最后一条消息应该首先显示。

HTML:

<ul>
        <li *ngFor="let reply of message_show.messages">
          <img [src]="reply.from_user_image || '../assets/images/msg.png'"/>
          <p><b>{{reply.name}} </b> <span> {{reply.updated_at | date:'dd.MM.yyyy'}} - {{reply.updated_at | date:'h:mm'}}</span></p>
          <p>{{reply.text}}</p>
        </li>
      </ul>

Ts:

loadMessages() {
    this.service
          .getMessages()
          .subscribe(
            data => {
              this.messagesdata = data;
              this.activeMessages = data.filter(msg => msg.active == true && msg.from_user_name !== 'Anonymus' && msg.messages.length > 0)
              this.closedMessages = data.filter(msg => msg.active == false && msg.from_user_name !== 'Anonymus' && msg.messages.length > 0);
              if (this.activeMessages.length > 0) {
                if(!this.message_show) {
                  var test = this.message_show = this.activeMessages[0];
                  this.message = true;
                  this.message_id = this.activeMessages[0].id;
                  this.message_show.messages.map(function(msg) {
                    if(msg.from_user_id == test.from_user_id) {
                      msg.from_user_image = test.from_user_image;
                    } else {
                      msg.from_user_image = test.to_user_image;
                    }
                    if(msg.to_user_id == test.to_user_id) {
                      msg.to_user_image = test.to_user_image;
                    } else {
                      msg.to_user_image = test.to_user_image;
                    }
                  })
                }
              }             
            },error => {});
  }

Answer 1

这是一个有角度的解决方案:

我添加了#scrollCottom模板变量。

您可以使用ViewChild获取Element引用，并应检查滚动底部问题。

组件；

import { AfterViewChecked, ElementRef, ViewChild, OnInit} from 'angular2/core'
@Component({
    ...
})
export class YourComponent implements OnInit, AfterViewChecked {
    @ViewChild('scrollBottom') private scrollBottom: ElementRef;

    ngOnInit() {
        this.scrollToBottom();
    }

    ngAfterViewChecked() {        
     this.scrollToBottom();        
    } 

    scrollToBottom(): void {
        try {
            this.scrollBottom.nativeElement.scrollTop = this.scrollBottom.nativeElement.scrollHeight;
        } catch(err) { }
    }
}

HTML:

<ul #scrollBottom>
  <li *ngFor="let reply of message_show.messages">
    <img [src]="reply.from_user_image || '../assets/images/msg.png'"/>
    <p><b>{{reply.name}} </b> <span> {{reply.updated_at | date:'dd.MM.yyyy'}} - {{reply.updated_at | date:'h:mm'}}</span></p>
    <p>{{reply.text}}</p>
  </li>
</ul>