Using comma as a list separator in Angular 2

Question

I like Eric’s answer better (see his comment for a sample Plunker):

<span *ngFor="let item of items; let isLast=last">
   {{item}}{{isLast ? '' : ', '}}
</span>

My original answer was to use the optional index in the NgFor microsyntax:

<span *ngFor="#item of items, #i=index">
   {{item}}{{i === items.length - 1 ? '' : ', '}}
</span>

An alternative is to use just use CSS ::before syntax, as described here: https://stackoverflow.com/a/31805688/215945