UC Santa Cruz

Despite the prevalence of JavaScript in modern web development, most JavaScript optimizations are designed to improve run-time. However, the load-time of websites is also an important aspect of a user’s experience. Therefore, it would be advantageous to have a method for significantly decreasing the amount of time it takes to load webpages.

We propose LiveJS: a tool that utilizes seamless profiling information to modify the order and method JavaScript functions are sent to the client, thus providing a speedup in loading time. The initial JavaScript response LiveJS sends to the user is shorter, as the definitions of most of the JavaScript functions have been removed or delayed. Following that, the rest of the used functions are sent in an asynchronous response from the server. Because the initial file size is smaller, the web browser is able to start compiling and even running the JavaScript code it has before the rest of the data has even finished downloading. The evaluation shows the speedups with highly optimized websites like the Google calendar and the Amazon website, showing an average of more than 20% load time reduction across all benchmarks.