app.component.ts

 
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app';
  
  stock = ""

}

app.component.html

<h1>組件間的通信</h1>
<div>我是父組件</div>
<div>
    <input type="text" placeholder="請輸入股票代碼" [(ngModel)]="stock">
    <app-order [stockCode]="stock" [amount]="100"></app-order>
</div>

order.component.ts

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

@Component({
  selector: 'app-order',
  templateUrl: './order.component.html',
  styleUrls: ['./order.component.css']
})
export class OrderComponent implements OnInit {
  
  @Input()
  stockCode:string;

  @Input()
  amount: number

  constructor() { }

  ngOnInit() {
  }

}

order.component.html

<div>
  我是子組件
</div>
<div>
  買{{amount}}手{{stockCode}}股票
</div>