With this plugin, you can use something like DefinePlugin.runtimeValue in Webpack3.
npm i --save-dev define-constant-plugin
webpack.config.js
const DefineConstantPlugin = require('define-constant-plugin')
module.exports = {
entry: 'index.js',
plugins: [
new DefineConstantPlugin({
'process.env': DefineConstantPlugin.runtimeValue(Date.now, {
fileDependencies: [fileDep],
})
})
],
}