Configuration.resolve has an unknown property ‘root’

resolve.root is Webpack 1 configuration and doesn’t exist for Webpack 2.

For Webpack 2 you can use resolve.modules: https://webpack.js.org/configuration/resolve/#resolve-modules

module.exports= {
  entry:'./public/app.jsx',
  output: {
    path: __dirname,
    filename:'./public/bundle.js'
  },
  resolve: {
    modules: [__dirname, 'node_modules'],
    alias:{
      Mod1: 'public/components/mod1.jsx',
      Mod2:'public/components/mod2.jsx',
      Mod3: 'public/components/mod3.jsx'
    },
    extensions: ['*','.js','.jsx']
  },
  module :{
    rules:[{
      use : 'babel-loader',
      query :{
        presets:['react','es2015','es2017']
      },
      test: /\.jsx?$/,
      exclude: /(node_modules|bower_components)/
    }]
  }
};

I’ve also updated module.loaders -> module.rules as this is deprecated in Webpack 2.