打字稿和角度2

Question

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

import { Grocery } from '../../auth/grocery.model';

export interface CartItem {
grocery: Grocery;
  count: number;
 amount: number;
 }

 export class Cart {
count: number = 0;
amount: number = 0;
  items: CartItem[] = [];
  }


  @Injectable()
  export class CartService {
  cart: Cart = new Cart(); 
  constructor(){}
  /* constructor(private Cart: Cart) {
  this.cart = Cart;
  }*/

  addGrocery(grocery: Grocery) {
  console.log(this.cart);
  console.log("gro" + grocery);
  console.log(grocery.sno);
  let item: CartItem = this.findItem(grocery.sno);
  console.log("first" + item);
  if (item) {
  item.count++;
  item.amount += grocery.cost;
  console.log("item" + item.amount);
  } else {
  item = {
    grocery: grocery,
    count: 1,
    amount: grocery.cost
  };
  console.log("else" + this.cart.items.push(item));
  this.cart.items.push(item);
  }
  this.cart.count++;
  this.cart.amount += grocery.cost;
  console.log("cart" + this.cart.amount);
  console.log(item);
  console.log(this.cart);
  return item;
  }

  removeProduct(grocery: Grocery) {
  let item: CartItem = this.findItem(grocery.sno);
  if (item) {
  item.count--;
  item.amount -= grocery.cost;
  if (!item.count) {
    this.remove(item);
  }
  this.cart.count--;
  this.cart.amount -= grocery.cost;
}

return item;
}

removeItem(item: CartItem) {
this.remove(item);
this.cart.count -= item.count;
this.cart.amount -= item.amount;
}

findItem(id: string): CartItem {
for (let i = 0; i < this.cart.items.length; i++) {
  if (this.cart.items[i].grocery.sno === id) {
    return this.cart.items[i];
  }
}
return null;
}

clearCart() {
this.cart.items = [];
this.cart.amount = 0;
this.cart.count = 0;
}

remove(item: CartItem) {
let indx: number = this.cart.items.indexOf(item);
if (indx !== -1) {
  this.cart.items.splice(indx, 1);
}
}
}

从另一个组件调用cart变量时，购物车显示为空，且值不会增加。

addGrocery(grocery: Grocery) {
console.log(this.cart);
console.log("gro" + grocery);
console.log(grocery.sno);
let item: CartItem = this.findItem(grocery.sno);
console.log("first" + item);
if (item) {
  item.count++;
  item.amount += grocery.cost;
  console.log("item" + item.amount);
} else {
  item = {
    grocery: grocery,
    count: 1,
    amount: grocery.cost
  };
  console.log("else" + this.cart.items.push(item));
  this.cart.items.push(item);
}
this.cart.count++;
this.cart.amount += grocery.cost;
console.log("cart" + this.cart.amount);
console.log(item);
console.log(this.cart);
return item;
}

在上面的代码中，正在进行增量 但是在下面的代码中，它从另一个组件调用购物车时显示初始值

@Injectable()
export class CartService {
cart: Cart = new Cart(); 
constructor(){}