How webpack.config.js work in react project?

I saw react + express project code here, start project just using this codes.

• rm -rf build public/bundle.js
• ./node_modules/.bin/babel server --out-dir build
• ./node_modules/.bin/webpack --progress
• node ./build/main.js"

But I can't find how to read/execute webpack.config.js command. Who read this code? and how it works?

Webpack reads webpack.config.js by default, unless you explicitly tell it to read another config file by using the --config argument, e.g.:

webpack --config another.config.js

In your case, this command reads the webpack.config.js:

./node_modules/.bin/webpack --progress