MEAN堆栈应用程序：列的总和

Question

所以我有一个普通的堆栈应用程序，其中包含并订购包含以下内容的数组：名称，描述，成本，状态。

我打算在此表中添加“新订单”，并希望更新该表中所有成本之和的总成本。并非100％如何做到这一点。

**Here is my html**

https://i.stack.imgur.com/I28ze.png

**HERE is the typescript file:**

import { Component, OnInit } from '@angular/core';
import { ApiService } from './../../service/api.service';

@Component({
  selector: 'app-order-list',
  templateUrl: './order-list.component.html',
  styleUrls: ['./order-list.component.css']
})

export class OrderListComponent implements OnInit {

  Order: any = [];

  constructor(private apiService: ApiService) {
    this.readOrder();
  }

  ngOnInit() {}

  readOrder(){
    this.apiService.getOrders().subscribe((data) => {
     this.Order = data;
    });
  }

  removeOrder(order, index) {
    if (window.confirm('Are you sure?')) {
        this.apiService.deleteOrder(order._id).subscribe((data) => {
          this.Order.splice(index, 1);
        }
      );
    }
  }

}

**and here is the orders arrary:**
export class Order {
  name: string;
  description: string;
  cost: number;
  status: string;
}