index in ng for
You have to use let to declare the value rather than #.
<ul>
<li *ngFor="let item of items; let i = index" [attr.data-index]="i">
{{item}}
</li>
</ul>
Angular = 1
<ul>
<li *ngFor="#item of items; #i = index" [attr.data-index]="i">
{{item}}
</li>
</ul>