input loses focus when editing value. Using ngFor and ngModel. Angular5

Issue

I have a simple list that binds two-way to a parameter hero in hero.component.ts.

Though when I start typing in the input field it loses focus and I have to click it again. What am I supposed to do in order to allow the user edit the input value without the input field loses target?

 <li *ngFor="let power of hero.powers; let i = index">
      <input [(ngModel)]="hero.powers[i]"/>
 </li>

Solution

Using trackBy function of angular fixes the issue.

live example showing it

<hello name="{{ name }}"></hello>
<div>
   <li *ngFor="let power of hero.powers; let i = index; trackBy: trackByFn">
  <input [(ngModel)]="hero.powers[i]"/>
   </li>
</div>

component file

trackByFn(index, item) {
  return index;  
}

Answered By - Franklin Pious