gulpfile.js

var gulp = require("gulp"),
    closureCompiler = require('gulp-closure-compiler');

gulp.task('compress', function() {
  gulp.src("src/**/*.js")
    .pipe(closureCompiler({
      // compilerPath is optional, since google-closure-compiler is a dependency
      // compilerPath: 'bower_components/closure-compiler/lib/vendor/compiler.jar',
      fileName: 'client.min.js',
      compilerFlags: {compilation_level: 'SIMPLE_OPTIMIZATIONS'}
    }))
    .pipe(gulp.dest('dist'));
});

gulp.task("default", ["compress"], function() {});