ngFor

*ngFor="let user of users" 
*ngFor="let obj of setData.items;let i = index"
<div *ngFor=" let tweet of singleCategory;  let i=index">
    <div *ngIf="i<2">
        {{tweet}}
    </div>
</div>
<ion-option *ngFor="#name of namesList" [value] = "name.shortName">{{name.shortName}}</ion-option>

ngFor trackBy

ngfor 의 최적화를 위해

*ngFor='let student of students; 
trackBy:trackByStudentID; 
let i=index; 
let isFirst = first; 
let isLast = last, 
let isEven = even; 
let isOdd = odd'