1、運行：npm install less --save-dev

2、由于高版本的less-loader容易報錯，所以我使用的是5.0.0版本的，
運行：npm install less-loader@5.0.0 --save-dev

3、配置webpack.config.js文件
（如果沒有這個js文件，請先運行：npm run eject）

找到下面這段代碼:

image.png

在這下面直接添加以下代碼：

const lessRegex = /\.less$/;
const lessModuleRegex = /\.module\.less$/;

找到下面這段代碼：

image.png

可以看到關于sass部分的配置，增加less配置就是把sass那部分復制粘貼改成less就行了，下面是我改好的，可作參考：

       {
              test: sassRegex,
              exclude: sassModuleRegex,
              use: getStyleLoaders(
                {
                  importLoaders: 3,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                },
                'sass-loader'
              ),
              // Don't consider CSS imports dead code even if the
              // containing package claims to have no side effects.
              // Remove this when webpack adds a warning or an error for this.
              // See https://github.com/webpack/webpack/issues/6571
              sideEffects: true,
            },
            {
              test: lessRegex,
              exclude: lessModuleRegex,
              use: getStyleLoaders(
                {
                  importLoaders: 2,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                },
                'less-loader'
              ),
              // Don't consider CSS imports dead code even if the
              // containing package claims to have no side effects.
              // Remove this when webpack adds a warning or an error for this.
              // See https://github.com/webpack/webpack/issues/6571
              sideEffects: true,
            },
            // Adds support for CSS Modules, but using SASS
            // using the extension .module.scss or .module.sass
            {
              test: sassModuleRegex,
              use: getStyleLoaders(
                {
                  importLoaders: 3,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                  modules: {
                    getLocalIdent: getCSSModuleLocalIdent,
                  },
                },
                'sass-loader'
              ),
            },
            {
              test: lessModuleRegex,
              use: getStyleLoaders(
                {
                  importLoaders: 2,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                  modules: {
                    getLocalIdent: getCSSModuleLocalIdent,
                  },
                },
                'less-loader'
              ),
            },

4、新建一個樣式文件，比如login.less

image.png

5、在login.jsx組件引用此樣式：

image.png