node.js - Based on dvajs, how can I get the current environment in the code?

Question

How can I get the current environment in the code? For example, when I develop, I want to simulate the results of user input...such as the results of scanning a QR code...

I read a few webpack configuration files and it said that node_env can be obtained. But no matter how I configure it, it has no effect...

if(ENV=='dev'){
console.log('开发环境');
}
else{
console.log('生产环境');
}

thank you all.

怪我咯 · Answer

webpack has a plug-in

new webpack.DefinePlugin({
            'ENV': '"production"'
        })