react项目need an appropriate loader to handle this file type

Question

react项目报错：

    You may need an appropriate loader to handle this file type.
    |
    > ReactDOM.render(<App />, document.getElementById("app"));

webpack

    {
                test: /\.js$/,
                exclude: "/node_modules/",
                use: ["babel-loader"]
            },

.babelrc:

    {
      "presets": ["env", "react"]
    }

index.js

    import React from "react";
    import ReactDOM from "react-dom";
    import App from "./components/App";
    
    import "./styles/index.scss";
    
    ReactDOM.render(<App />, document.getElementById("app"));

Answer 1

babel里面要配置支持jsx语法

npm install babel-preset-react --save-dev

{
    presets: ['es2015', 'react']
}

Answer 2

安装 sass-loader