Intel Labs’ Parallel JavaScript is a data-parallel programming model that allows JavaScript pro- grams to use hardware parallelism such as multiple cores, vector instructions, and GPUs, which have previously been inaccessible to Web applications. In order to demonstrate the advantages of Parallel JavaScript, we have used it to create a fast, reusable, open-source computer vision library. We then used this library to build a real- time, interactive hand gesture detection application.