Angular 2+ - check if Pipe returns an empty subset of original list

This is my code which modified a bit from @Günter Zöchbauer

<div  *ngFor="let filter_list of list | FilterItem" >
    <div *ngIf=" filter_list == -1 " class="alert alert-info">No item found</div>    
    <div *ngIf="filter_list !== -1" *ngFor="let item of filter_list  ; let i = index;" >
        {{ item }}
    </div>
</div>

Pipe code

@Pipe({
  name: 'FilterItem'
})
export class FilterItem {

  transform(list, args?) {
       let result = ...; 
       if ( result && result.length > 0 ){
          return [ result ];
       }else{
          return [ -1 ];
       }
  }
}

One more way to achieve this is to check the html element for children or in my case the table for rows.

<table #myTable>
  <tr *ngFor="let item of list | somePipe : searchText">
      <td>{{ item.name }}</td>
  </tr>
</table>

<p *ngIf="!myTable.rows.length">No results</p>

<div *ngIf="(list | search: searchTerm).length === 0">
  "No matches"
</div>
<div *ngFor="#item in list | search: searchTerm">{{ item }}</div>

Alternatively you could modify your pipe to return a specific token that indicates that the list is empty

@Pipe({
  name: 'search'
})
export class SearchPipe {

  transform(value, searchTerm) {
    let result = ...
    if(result.length === 0) {
      return [-1];
    }
    return result;
  }
}

<ng-container *ngFor="let item of list | search: searchTerm">
  <div *ngIf="item === -1">"No matches"</div>
  <div *ngIf="item !== -1">{{ item }}</div>
</ng-container>