如何在模板 Angular 中增加变量？

Question

I have the following template:

<ng-container *ngFor="let documentsGroup of documents | groupBy: 'doctype'"><
   <tr *ngFor="let doc of documentsGroup.value; let i = index">{{num}</tr>
</ng-container>

I know that it is not good to call {{num}} in template, because it will be rendered each time.

Component is:

public t = 1;
public get num() {
    return this.t++;
}

So, how to create variable num in template and increment it like {{num++}} ?

Answer 1

I have created a simple example. But I recommend you use it in the component which change detection strategy changed to the onPush .

Here is the link to the stackblitz example. https://stackblitz.com/edit/ngfor-example-rad9zs?file=app%2Fapp.component.html