webpack报错信息(一)

- configuration.module has an unknown property 'mode'. These properties are valid: object { defaultRules?, exprContextCritical?, exprContextRecursive?, exprContextRegExp?, exprContextRequest?, generator?, noParse?, parser?, rules?, strictExportPresence?, strictThisContextOnImports?, unknownContextCritical?, unknownContextRecursive?, unknownContextRegExp?, unknownContextRequest?, unsafeCache?, wrappedContextCritical?, wrappedContextRecursive?, wrappedContextRegExp? } -> Options affecting the normal modules (NormalModuleFactory).

webpack打包，记录一下报错信息。

报错原因：层级问题

module.exports = {
//请注意,entry,output,module,plugins,mode是同一层级的.
  entry: "./src/index.js",
  output: {
    filename: "built.js",
    path: resolve(__dirname, " build"),
  },
  module: {
    rules: [
      //详细的loader配置
      {
        test: /\.css$/,
        use: [
          "style-loader",
          "css-loader",
        ],
      },
    ],
  },
  plugins: [
  ],
  mode: "development",
};