ngfor index

<ul>
    <li *ngFor="let item of items; let i = index" [attr.data-index]="i">
        {{item}}
    </li>
</ul>/*
ngFor with index in angular is used here for generating 'li' element till the studentDetails array length.
And also make a note if you are using angular 1 then you have to replace 'let' with '#', but its ok if you are using angular 2 or above.
*/

<ul>
    <li *ngFor="let student of studentDetails; index as i;" [attr.data-index]="i">
        {{student}}
    </li>
</ul>

/*
I hope it will help you.
Namaste
*/<ul>
    <li *ngFor="let item of items; let i = index" [attr.data-index]="i">
        {{item}}
    </li>
</ul><ul>
    <li *ngFor="let item of items; index as i">
        {{item}}
    </li>
</ul><ul>
    <li *ngFor="let item of items; let i = index" [attr.data-index]="i">
        {{item}}
    </li>
</ul><ul>
    <li *ngFor="let item of items; let i = index" [attr.data-index]="i">
        {{item}}
        {{i}}
    </li>
</ul>