webpack.config.js====CSS相关：css和scss配置loader

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1. 安装：

//loader加载器加载css和sass模块
cnpm install style-loader css-loader node-sass sass-loader --save-dev
//loader加载器加载css和less模块
cnpm install style-loader css-loader less less-loader --save-dev

//样式抽离文件 如果是webpack4.X 需要加@next
//现在webpack4.x支持mini-css-extract-plugin插件，但是目前不稳定
cnpm install --save-dev extract-text-webpack-plugin@next
cnpm install --save-dev mini-css-extract-plugin

2. webpack.config.js中使用

const extractTextWebpackPlugin = require('extract-text-webpack-plugin');
let cssExtract = new extractTextWebpackPlugin({
    filename: 'css/index.css',
    disable: false
});
let sassExtract = new extractTextWebpackPlugin({
    filename: 'css/public.css',
    disable: false
});

        rules: [
            //配置css加载器
            {

                test: /\.css$/,
                use: cssExtract.extract({
                    fallback: "style-loader",
                    use: ["css-loader", "postcss-loader"]
                })
            },
            //配置sass加载器
            {
                test: /\.scss$/,
                use: sassExtract.extract({
                    fallback: 'style-loader',
                    use: ['css-loader', "postcss-loader", 'sass-loader']
                })
            },
        ]