With the significant increase and the availability of functionality via mobile devices and applications, a key problem of limited computation capabilities and short-life battery has arisen, Mobile Cloud Computing(MCC) has been emerged as a potential solution to the limitations of mobile devices. Within MCC research, mobile JavaScript offloading has been proposed as a solution for saving energy on mobile devices. It achieves this by offloading computationally intensive tasks to the Cloud. In this paper, energy consumption is evaluated by offloading JavaScript applications from mobile devices to cloud servers. The experiments are carried out by offloading computation intensive sorting functions. The results show the energy-efficiency of mobile JavaScript offloading on mobile device and also imply some factors affecting mobile JavaScript offloading.