webpack --optimize-minimize --define process.env.NODE_ENV="'production'"

var gulp = require('gulp');
var webpackStream = require('webpack-stream');
var webpack2 = require('webpack');

gulp.task('default', function() {
  var options = {
    plugins: [
      new webpack2.DefinePlugin({
        'process.env': { 'NODE_ENV': "'production'" }
      }),
      new webpack2.optimize.UglifyJsPlugin()
    ]
  };
  return gulp.src('src/entry.js')
    .pipe(webpackStream(options, webpack2))
    .pipe(gulp.dest('dist/'));
});