Loop Iteration Indexes in Angular

When looping through *ngFor and @for, you can get not only the array elements, but also their numbers. Let's see how this is done. Let's say we have an array in the main component:

export class AppComponent {
	public arr: string[] = ['a', 'b', 'c', 'd'];
}

Let's print both its elements and numbers.

For the *ngFor directive, a special trick is used for this:

<ul>
	<li *ngFor="let el of arr; let i = index">
		{{ i }}
		{{ el }}
	</li>
</ul>

And for the @for construction, you can simply take and use this variable inside the loop:

<ul>
	@for (el of arr; track $index) {
		<li>
			{{ $index }}
			{{ el }}
		</li>
	}
</ul>

Given an array:

export class AppComponent {
	public arr: string[] = ['a', 'b', 'c', 'd'];
}

Print its numbers, but so that they start with one, not zero.