NGFOR INDEX
<ul>
<li *ngFor="let item of items; let i = index" [attr.data-index]="i">
{{item}}
</li>
</ul>
2 Programmers 1 Bug
<ul>
<li *ngFor="let item of items; let i = index" [attr.data-index]="i">
{{item}}
</li>
</ul>
<li *ngFor="let item of items; index as i; trackBy: trackByFn">...</li>
<td *ngFor="let col of options.cols;index as i">
{{item[i]}} //Angular solution
</td>//for
<div *ngFor='let [data] of [dataArray]; let i=index;'>
<h2> {{i}} {{data.title}} </h2>
<img src='{{data.image}}' />
</div>
//the data contained in an array will be displayed element by element
//similar to the function .map() in React
<li *ngFor="let item of items; index as i; trackBy: trackByFn">...</li>