babel-loader7版本问题

　1.要安装的包

　　 第1套包：npm i babel-core babel-loader@7 babel-plugin-transform-runtime –D(千万记得是babel-loader@7)

 　　第2套包：npm I babel-preset-env babel-preset-stage-0 –D(注意是-零，不是字母o)

    这里babel-loader一定要加版本号7，否则下载的将是最新版本8

    babel版本如下所示：

{
  "name": "01-webpack-base",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev": "webpack-dev-server --open chrome --port 8888 --hot --host 127.0.0.1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "babel-core": "^6.26.3",
    "babel-loader": "^7.1.5",
    "babel-plugin-transform-runtime": "^6.23.0",
    "babel-preset-env": "^1.7.0",
    "babel-preset-react": "^6.24.1",
    "babel-preset-stage-0": "^6.24.1",
    "html-webpack-plugin": "^4.3.0",
    "webpack": "^4.43.0",
    "webpack-cli": "^3.3.11",
    "webpack-dev-server": "^3.11.0"
  },
  "dependencies": {
    "react": "^16.13.1",
    "react-dom": "^16.13.1"
  }
}