角度2中的目标特定元素

Question

如何仅在特定元素成为目标时应用方法？

有没有办法我只能传递一个应用于多个元素的方法，并且只在特定元素作为目标时触发它？

请参阅下面的示例代码。

aside.component.ts

subNavDisplayTitle ="";
subNavDisplay = "";

changeStyle(event) {
    if (this._opened === false) {
      this.subNavDisplay = event.type == 'mouseover' ? 'showSubMenu' : 'sub-nav';
      this.subNavDisplayTitle = event.type == 'mouseover' ? 'showSubMenuTitle' : 'sidebar-title';
    }
  }

aside.component.html

<ul class="nav">
        <li (mouseover)="changeStyle($event)" (mouseout)="changeStyle($event)">
            <div  class="sidebar-title" [ngClass]="subNavDisplayTitle">
              <b>Maintenance</b>
            </div>
            <ul [ngClass]="subNavDisplay">
              <li routerLinkActive="visitted"><a routerLink="storageentry">Storage</a></li>
              <li><a>Document type</a></li>
              <li routerLinkActive="visitted"><a routerLink="documentfile">Document file</a></li>
              <li><a>User access</a></li>
            </ul>
        </li>

        <li (mouseover)="changeStyle($event)" (mouseout)="changeStyle($event)">
            <div  class="sidebar-title" [ngClass]="subNavDisplayTitle">
              <b>Maintenance</b>
            </div>
            <ul [ngClass]="subNavDisplay">
              <li routerLinkActive="visitted"><a routerLink="uploadfile">File upload</a></li>
              <li routerLinkActive="visitted"><a routerLink="borrowdocument">Borrow document</a></li>
              <li><a>Document transfer</a></li>
            </ul>
        </li>

        <li (mouseover)="changeStyle($event)" (mouseout)="changeStyle($event)">
            <div  class="sidebar-title" [ngClass]="subNavDisplayTitle">
              <b>Maintenance</b>
            </div>
            <ul [ngClass]="subNavDisplay">
              <li routerLinkActive="visitted"><a routerLink="documentlist">Document list</a></li>
              <li routerLinkActive="visitted"><a routerLink="documentlocation">Document location</a></li>
              <li><a>Document Transaction</a></li>
            </ul>
        </li>
      </ul>

这是我悬停侧边栏导航时发生的事情 See Sample

the CSS