reactjs - preprocessor-loader not working in webpack-2 -

i following post set development , production variable using define plugin , app.js

//@if process.env.production  console.log("hi dev")  //@endif console.log(process.env.production); console.log("this working") 

while console showing value true if condition failed. here m script package.json

 "scripts": {     "build": "rimraf dist && cross-env node_env=production webpack",     "dev": "cross-env node_env=development  webpack-dev-server"   } 

and webapck config

 {         test: /\.jsx?$/,         exclude: /(node_modules|bower_components)/,         loader: 'babel-loader!preprocess-loader?+debug',        } 

and more situation happened me if change script this

"scripts": {         "build": "rimraf dist && cross-env node_env=development webpack",         "dev": "cross-env node_env=development  webpack-dev-server"       } 

and app,js if consoling process.env.development or process.env.production showing undefined rather true or false. please me out this