common.js

var $ = require('jquery');

gulpfile.js

var browserify = require('browserify');
var shim = require('browserify-shim');
var gulp = require('gulp');
var source = require('vinyl-source-stream');

var createCommonBundle = function() {
	var inst = browserify();
	inst .add(require.resolve('./js/common.js'))
	.bundle()
	.pipe(source('common.js'))
	.pipe(gulp.dest('../public/js/'));
};


gulp.task('default', function() {
		gulp.src('./components/modernizr/modernizr.js')
			.pipe(gulp.dest('../public/js/'));
		
		createCommonBundle();
});

package.json

	"browserify": {
		"transform": [ "browserify-shim" ]
	},
	"browser": {
		"jquery"    :  "./components/jquery/jquery.js",
		"bootstrap" :  "./components/bootstrap/dist/js/bootstrap.js"
	},
	 "browserify-shim": {
		"jquery"    :  {
			"exports" : "$"
		}
	}