app / mocks.ts（1,2）：错误TS1109：预期的表达式

Question

我正在学习Angular，过了一段时间我用 mocks.ts 文件遇到了这个问题：

1） mocks.ts 看起来像这样：

@import { Races } from './races';

export const RACES: Races[] = [{
    "id": 1,
    "name": "Daytona Thunderdome",
    "date": new Date('2512-01-04T14:00:00'),
    "about": "Race through the ruins of an ancient Florida battle arena.",
    "entryFee": 3200,
    "isRacing": false
  }, {
    "id": 2,
    "name": "San Francisco Ruins",
    "date": new Date('2512-07-03T20:00:00'),
    "about": "Drift down the streets of a city almost sunk under the ocean.",
    "entryFee": 4700,
    "isRacing": true
  }, {
    "id": 3,
    "name": "New York City Skyline",
    "date": new Date('2512-07-12T21:00:00'),
    "about": "Fly between buildings in the electronic sky.",
    "entryFee": 4300,
    "isRacing": true
  }];

2）我从races.ts文件中导入种族，如下所示：

  export class Races {
    "id": number;
    "name": string;
    "date": string;
    "about": string;
    "entryFee": number;
    "isRacing": boolean;
}

3）而且我将 RACES 导入 races.component.ts ，如下所示：

import { Component } from '@angular/core';
import { Races } from './races';
import { RACES } from './mocks';

@Component({
    selector: 'races',
    templateUrl: 'app/races.component.html',
    styleUrls: ['app/races.component.css']
})
export class RacesComponent {
  races: Races[];
  cash = 10000;
  ngOnInit() {
      this.races = RACES;
  };
  // Write your function here
  totalCost() {
      var sum = 0;
      for(let race of this.races) {
          if(race.isRacing) {
              sum += race.entryFee;
          }
      }
      return sum;
  };
}

非常感谢任何帮助！ 谢谢！