loader

安装

yarn add css-loader
yarn add style-loader
or
npm i style-loader css-loader

index.js

import "./css/index.css"

webpack.config.js

const path = require("path");
module.exports = {
    entry: "./index.js",
    output: {
        filename: "bundle.js",
        path:path.join(__dirname,"dist")
    },
    module: {
        rules: [
            {
                test: /\.css$/,
                use: [
                    'style-loader',
                    'css-loader'
                ]
            }
        ]
    },
    mode:"development"
}

css/index.css

div{
    width: 200px;
    height: 200px;
    background-color: red;
}

也可以打包图片

div{
    width: 200px;
    height: 200px;
    background: url("../images/4.png");
}

npm start  
index.html页面  alt+b  查看

处理图片

yarn add url-loader

webpack.config.js

const path = require("path");
module.exports = {
    entry: "./index.js",
    output: {
        filename: "bundle.js",
        path:path.join(__dirname,"dist")
    },
    module: {
        rules: [
            {
                test: /\.css$/,
                use: [
                    'style-loader',
                    'css-loader'
                ]
            },
            {
                test: /\.(png|jpg|gif)$/i,
                use: ["url-loader"]
            }
        ]
    },
    mode:"development"
}