my output of error:

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema. - configuration.module has an unknown property 'loaders'. These properties are valid: object { exprContextCritical?, exprContextRecursive?, exprContextRegExp?, exprContextRequest?, noParse?, rules?, defaultRules?, unknownContextCritical?, unknownContextRecursive?, unknownContextRegExp?, unknownContextRequest?, unsafeCache?, wrappedContextCritical?, wrappedContextRecursive?, wrappedContextRegExp?, strictExportPresence?, strictThisContextOnImports? } -> Options affecting the normal modules (NormalModuleFactory).

my webpack.config.js:

var webpack = require('webpack');
var path = require('path');

var BUILD_DIR = path.resolve(__dirname, 'src/client/public');
var APP_DIR = path.resolve(__dirname, 'src/client/app');

var config = {
  entry: APP_DIR + '/index.jsx',
  module : {
    loaders : [
      {
        test : /\.jsx?/,
        include : APP_DIR,
        loader : 'babel-loader'
      }
    ]
  },
  output: {
    path: BUILD_DIR,
    filename: 'bundle.js'
  }

};


module.exports = config;

my webpack version:

webpack@4.1.1