In recent years, web applications have become pervasive. Their backbone is JavaScript, the only programming language supported by all major web browsers. Most browsers run on desktop or mobile devices with parallel hardware. However, JavaScript is by design sequential, and current web applications make little use of hardware parallelism. Are web applications ready to exploit parallel hardware? To answer this question we take a two-step approach. First, we survey 174 web developers regarding the potential and challenges of using parallelism. Then, we study the performance and computation shape of a set of web applications that are representative for the emerging web. To this end, we developed an automated profiling and dependence analysis tool. Using the tool, we identify performance bottlenecks and examine memory access patterns to determine possible data parallelism. Our findings indicate that emerging web applications do have latent data parallelism, and JavaScript developers’ p...