Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
527 views
in Technique[技术] by (71.8m points)

angular2 template - Angular 2: How to write a for loop, not a foreach loop

Using Angular 2, I want to duplicate a line in a template multiple times. Iterating over an object is easy, *ngFor="let object of objects". However, I want to run a simple for loop, not a foreach loop. Something like (pseudo-code):

{for i = 0; i < 5; i++}
  <li>Something</li>
{endfor}

How would I do this?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

You could dynamically generate an array of however time you wanted to render <li>Something</li>, and then do ngFor over that collection. Also you could take use of index of current element too.

Markup

<ul>
   <li *ngFor="let item of createRange(5); let currentElementIndex=index+1">
      {{currentElementIndex}} Something
   </li>
</ul>

Code

createRange(number){
  // var items: number[] = [];
  // for(var i = 1; i <= number; i++){
  //   items.push(i);
  // }
  // return items;
  return new Array(number);
}

Demo Here

Under the hood angular de-sugared this *ngFor syntax to ng-template version.

<ul>
    <ng-template ngFor let-item [ngForOf]="createRange(5)" let-currentElementIndex="(index + 1)" [ngForTrackBy]="trackByFn">
      {{currentElementIndex}} Something
    </ng-template>
</ul>

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

1.4m articles

1.4m replys

5 comments

56.9k users

...