Increasingly, smartphones are becoming one of the most popular mobile devices in the personal computing environment. As the need for a variety of mobile applications increases, the target mobile platform is a primary concern for mobile application developers. To reduce design complexity for different platforms and enhance the compatibility of applications on various mobile OSes, a JavaScript-based web environment became a main target framework for smartphone applications. Two particular characteristics of a smartphone are restricted power supply and low-end hardware resources, compared to high-end servers. Computing-intensive and rich graphics-based applications in a smartphone may fully utilize the CPU and consume a large amount of the battery power accordingly. In this paper, we propose a platform-independent mobile offloading system, which is a delegated system for a web centric devices environment. Our offloading architecture uses a built-in proxy system that splits the original JavaScript-based application codes into the following two parts: a lightweight code for the mobile client and a computationally heavy code that runs on the server system. We adopt one of the web applications utilizing a combinatory search for our case study. Our evaluation shows that our mobile offloading system reduces the response time of the application running in the web browser and enables a high workload application to run on relatively low-end mobile devices. In addition, this method reduces power consumption of the device. Therefore, this web-based offloading architecture creates a new mobile computing environment and supports various OS platforms of mobile clients.