reate-react-app: webpack定义全局scss变量

npm i sass-resources-loader --save-dev

webpack.config.js添加配置：

__dirname:当前文件路径

{
              test: sassRegex,
              exclude: sassModuleRegex,
              use: [...getStyleLoaders(
                {
                  importLoaders: 3,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                },
                'sass-loader'
              ), {
                loader: require.resolve('sass-resources-loader'),
                options: {
                  resources: [path.resolve(__dirname, '../src/styles/common/variables.scss')]
                }
              }]