Angular2 ngFor adding numbers from index ++

Question

Am trying to increment the index value to create a list with numbers 1,2,3,4

<tbody>
    <tr *ngFor="let item of queue.truckQueus; let i = index" [attr.data-index]="i">
      <td>{{i ++ }}</td> //this throws an error
      <td>{{item.truck.reg_no}}</td>
    </tr>
</tbody>

How do i add the numbers from 1

I have also tried adding via

{{i += 1}}

But am always getting an error expression is expected. Where am i going wrong?

Hmm I've never tried it before .. but maybe create a function in your .ts file that will do the calculation and returns it? So in the view you would have {{ calc(i) }} — fransyozef
– fransyozef, Commented Aug 1, 2018 at 11:49

Mark Hughes · Accepted Answer · 2018-08-01 12:32:38Z

1

<tbody>
    <tr *ngFor="let item of queue.truckQueus; let i = index" [attr.data-index]="i">
      <td>{{i + 1 }}</td>
      <td>{{item.truck.reg_no}}</td>
    </tr>
</tbody>

This must work.

As mentioned in the docs.

JavaScript expressions that have or promote side effects are prohibited, including:

assignments (=, +=, -=, ...)
new
chaining expressions with ; or ,
increment and decrement operators (++ and --)

Read Here

edited Aug 1, 2018 at 12:32

Mark Hughes

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answered Aug 1, 2018 at 11:52

manish kumar

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