...例如……

<div class="month" *ngFor="#item of myCollection; #i = index">
...
</div>

有可能做一些像……

<div class="month" *ngFor="#item of 10; #i = index">
...
</div>

...不诉诸于不优雅的解决方案,比如:

<div class="month" *ngFor="#item of ['dummy','dummy','dummy','dummy','dummy',
'dummy','dummy','dummy']; #i = index">
...
</div>

?


当前回答

下面是Angular的一些非常干净和简单的东西:

在.ts:

max = 10;    

. html:

<div *ngFor="let dummy of ','.repeat(max).split(','); index as ix">
   - {{ix + 1}}:
</div>

其他回答

使用自定义结构指令索引:

根据Angular文档:

createEmbeddedView Instantiates an embedded view and inserts it into this container. abstract createEmbeddedView(templateRef: TemplateRef, context?: C, index?: number): EmbeddedViewRef. Param Type Description templateRef TemplateRef the HTML template that defines the view. context C optional. Default is undefined. index number the 0-based index at which to insert the new view into this container. If not specified, appends the new view as the last entry.

当angular通过调用createEmbeddedView创建模板时,它也可以传递将在ng-template中使用的上下文。

使用context可选参数,你可以在组件中使用它, 在模板中提取它,就像你使用*ngFor一样。

app.component.html:

<p *for="number; let i=index; let c=length; let f=first; let l=last; let e=even; let o=odd">
  item : {{i}} / {{c}}
  <b>
    {{f ? "First,": ""}}
    {{l? "Last,": ""}}
    {{e? "Even." : ""}}
    {{o? "Odd." : ""}}
  </b>
</p>

for.directive.ts:

import { Directive, Input, TemplateRef, ViewContainerRef } from '@angular/core';

class Context {
  constructor(public index: number, public length: number) { }
  get even(): boolean { return this.index % 2 === 0; }
  get odd(): boolean { return this.index % 2 === 1; }
  get first(): boolean { return this.index === 0; }
  get last(): boolean { return this.index === this.length - 1; }
}

@Directive({
  selector: '[for]'
})
export class ForDirective {
  constructor(private templateRef: TemplateRef<any>, private viewContainer: ViewContainerRef) { }

  @Input('for') set loop(num: number) {
    for (var i = 0; i < num; i++)
      this.viewContainer.createEmbeddedView(this.templateRef, new Context(i, num));
  }
}

我认为简单而简短的解决办法就在这里。

你的my.component.ts文件

setArrayFromNumber(i: number) {
  return new Array(i);
}

你的my.component.html文件

<li *ngFor='let in of setArrayFromNumber(5); let i = index'>{{ i }}</li>

就是这样! !

你可以使用lodash:

@Component({
  selector: 'board',
  template: `
<div *ngFor="let i of range">
{{i}}
</div>
`,
  styleUrls: ['./board.component.css']
})
export class AppComponent implements OnInit {
  range = _.range(8);
}

我没有测试代码,但它应该工作。

@OP,你的“不优雅”解决方案已经非常接近了。

如何:

<div class="month" *ngFor="let item of [].constructor(10); let i = index">
...
</div>

这里我从一个空数组中获取Array构造函数:[]。构造函数,因为Array在模板语法中不是一个可识别的符号,而且我懒得像@pardeep-jain在他的第4个例子中那样在组件typescript中执行Array=Array或counter =Array。我调用它时不使用new因为new对于从array构造函数中获取数组来说是不必要的。

Array(30)和new Array(30)是等价的。

数组将为空,但这无关紧要,因为你实际上只是想在循环中使用i from;let i = index。

编辑以回复评论:

问:如何使用变量来设置NgFor循环的长度?

下面是一个关于如何呈现具有可变列/行的表的示例

<table class="symbolTable">
  <tr *ngFor="let f of [].constructor(numRows); let r = index">
    <td class="gridCell" *ngFor="let col of [].constructor(numCols); let c = index">
      {{gridCards[r][c].name}}
    </td>
  </tr>
</table>
export class AppComponent implements OnInit {
  title = 'simbologia';
  numSymbols = 4;
  numCols = 5;
  numRows = 5;
  guessCards: SymbolCard[] = [];
  gridCards: SymbolCard[][] = [];

  ngOnInit(): void {
    for (let c = 0; c < this.numCols; c++) {
      this.guessCards.push(new SymbolCard());
    }

    for (let r = 0; r < this.numRows; r++) {
      let row: SymbolCard[] = [];

      for (let c = 0; c < this.numCols; c++) {
        row.push(
          new SymbolCard({
            name: '' + r + '_' + c
          }))
      }
      this.gridCards.push(row);
    }
  }
}

这也可以像这样实现:

HTML:

<div *ngFor="let item of fakeArray(10)">
     ...
</div>

打字稿:

fakeArray(length: number): Array<any> {
  if (length >= 0) {
    return new Array(length);
  }
}

演示工作