在我的例子中，我犯了从文档中复制*ng-for=的错误。

https://angular.io/guide/user-input

如果我错了，请指正。但是*ng-for=似乎已经被更改为*ngFor=

在我的例子中，我没有在for循环中声明循环变量

<div *ngFor="pizza of pizzas; index as i">

而不是

<div *ngFor="let pizza of pizzas; index as i">

在声明了“let”之后，它就对我有用了。

我忘记用“@Input”来注释我的组件(哎呀!)

html(违规代码):

<app-book-item
  *ngFor="let book of book$ | async"
  [book]="book">  <-- Can't bind to 'book' since it isn't a known property of 'app-book-item'
</app-book-item>

book-item.component.ts的修正版本:

import { Component, OnInit, Input } from '@angular/core';

import { Book } from '../model/book';
import { BookService } from '../services/book.service';

@Component({
  selector: 'app-book-item',
  templateUrl: './book-item.component.html',
  styleUrls: ['./book-item.component.css']
})
export class BookItemComponent implements OnInit {

  @Input()
  public book: Book;

  constructor(private bookService: BookService)  { }

  ngOnInit() {}

}

在我的例子中，=和"之间应该没有空格，

错误的:

*ngFor = "let talk of talks"

正确的:

*ngFor="let talk of talks"

另一个导致OP错误的拼写错误可以用在:

<div *ngFor="let talk in talks">

你应该用of代替:

<div *ngFor="let talk of talks">

使用这个

<div *ngFor="let talk of talks"> 
   {{talk.title}} 
   {{talk.speaker}}
   <p>{{talk.description}}</p>
</div>
    

您需要指定变量以遍历对象的数组