相关疑难解决方法(0)

更新到Angular 7.3.6后，在ng serve上出现以下错误：

./node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/jit-polyfills.js中的错误找不到模块：错误：无法解析“ core-js / es7 / reflect” '\ node_modules @ angular-devkit \ build-angular \ src \ angular-cli-files \ models'

这是我的package.json依赖项：

{
  "name": "frontend",
  "version": "0.0.0",
  "license": "MIT",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build --prod",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^7.2.11",
    "@angular/cdk": "^7.3.6",
    "@angular/common": "^7.2.11",
    "@angular/compiler": "^7.2.11",
    "@angular/core": "^7.2.11",
    "@angular/flex-layout": "^7.0.0-beta.24",
    "@angular/forms": "^7.2.11",
    "@angular/http": "^7.2.11",
    "@angular/material": "^7.3.6",
    "@angular/platform-browser": "^7.2.11",
    "@angular/platform-browser-dynamic": "^7.2.11",
    "@angular/router": "^7.2.11",
    "adm-zip": "^0.4.13", …

我已经将一个 Angular 项目从版本 7 更新到了 8。一切运行顺利，原理图完成了它的工作（也许），我们还好（项目甚至在生产中）。当我们更新 Angular CLI 时，我们总是会生成一个新项目来查看真正的差异并从中学习，例如新的依赖项、配置等。

使用 Angular CLI 8.0.4 生成新的 Angular 项目时，新应用程序没有core-js依赖项：

"dependencies": {
    "@angular/animations": "~8.0.1",
    "@angular/common": "~8.0.1",
    "@angular/compiler": "~8.0.1",
    "@angular/core": "~8.0.1",
    "@angular/forms": "~8.0.1",
    "@angular/platform-browser": "~8.0.1",
    "@angular/platform-browser-dynamic": "~8.0.1",
    "@angular/router": "~8.0.1",
    "rxjs": "~6.4.0",
    "tslib": "^1.9.0",
    "zone.js": "~0.9.1"
  }

core-js不存在对构建项目的分析包： 在我使用 Angular CLI 更新的旧项目中，core-js是否存在并且存在于最终包中：

"dependencies": {
    "@angular/animations": "~8.0.3",
    "@angular/cdk": "~8.0.1",
    "@angular/common": "~8.0.3",
    "@angular/compiler": "~8.0.3",
    "@angular/core": "~8.0.3",
    "@angular/forms": "~8.0.3",
    "@angular/platform-browser": "~8.0.3",
    "@angular/platform-browser-dynamic": "~8.0.3",
    "@angular/router": "~8.0.3",
    "@auth0/angular-jwt": "2.1.1",
    "@hackages/ngxerrors": "~8.0.0",
    "@ng-bootstrap/ng-bootstrap": "5.0.0-rc.1",
    "@ngx-loading-bar/core": …