Grunt min task with support for minification without concatenation (one-to-one)

grunt.js

    //.....
    min: { // for production
      vendor: {
        src: ['public/js/vendor/*.js'],
        dest: 'public_build/js/vendor.js',
        separator: ';'
      },
      app: {
        src: ['public/js/*.js'],
        destDir: 'public_build/js/',
        separator: ';'
      }
    },
    //.....

min.js

  grunt.registerMultiTask('min', 'Minify files with UglifyJS.', function() {
    var that = this
      , files = grunt.file.expandFiles(this.file.src)
      , banner
      , max
      , min;
      
    // Get banner, if specified. It would be nice if UglifyJS supported ignoring
    // all comments matching a certain pattern, like /*!...*/, but it doesn't.
    var banner = grunt.task.directive(files[0], function() { return null; });
    if (banner === null) {
      banner = '';
    } else {
      files.shift();
    }
    
    if (this.data.destDir) {
      // uglify single files, without concatenating
      files.forEach(function (file) {
        var dest = path.join(that.data.destDir, file.split('/').pop());
        var max = grunt.file.read(file);
        var min = grunt.helper('uglify', max, grunt.config('uglify'));
        
        grunt.file.write(dest, min);
        grunt.log.writeln('File "' +  dest + '" created.');
        grunt.helper('min_max_info', min, max);
        
      });
    } else {
      // concatenate and uglify
      max = grunt.helper('concat', files, {separator: this.data.separator});
      min = banner + grunt.helper('uglify', max, grunt.config('uglify'));
      grunt.file.write(this.file.dest, min);
      
      // Fail task if errors were logged.
      if (this.errorCount) {
        return false;
      } else {
        grunt.log.writeln('File "' + this.file.dest + '" created.');
        grunt.helper('min_max_info', min, max);
      }
    }    
  });