Best way to check for null values using *ngFor in Angular 2

Nevermind - this checks if the array is null, not elements within the array.

Instead of the custom pipe, you could just do a null check right in the *ngFor, I think it's pretty readable. You're just providing an empty array if performances is null:

<tr *ngFor="let performance of (performances ? performances : [])">

UPDATED on 03.01.2020

There are multiple ways.

Using only the template:

1. use empty array (or maybe some fallback array) if its undefined or null..:

<tbody>
    <tr *ngFor="let performance of (performances || [])">
      <td>{{ performance.id }}</td>
      ...
    </tr>
</tbody>

2. check it inline and use a default value:

<tbody>
    <tr *ngFor="let performance of performances">
      <td>{{ performance?.id || 1337 }}</td>
      ...
    </tr>
</tbody>

3. you could use *ngIf:

<tbody>
    <tr *ngFor="let performance of performances">
      <td *ngIf="performance?.id; else elsePerfId">{{ performance.id }}</td>
      <ng-template #elsePerfId>
        <td>default</td>
      </ng-template>
      ...
    </tr>
</tbody>

4. using a pipe and returning a default value:

<tbody>
    <tr *ngFor="let performance of (performances | defaultValueIfNullPipe)">
      <td>{{ performance.id }}</td>
      ...
    </tr>
</tbody>

Using Component..

You could also take care that there are no invalid values:

getFunds(){
    this._service.getData().then(
        performances => this.performances = performances || [] /* empty array or default value here */
    );
}