Concurrency control is difficult in JavaScript programs, where event race due to asynchronous computation is a major source of errors. While methods such as promises, cancellation tokens, and reactive programming each offer its own advantages in addressing this problem, none offers a complete solution.

In this work, we present an integrated solution for concurrency control of JavaScript using a library, arrowjs, which is based on the abstraction of arrows. Arrowjs uses continuation passing style to chain callbacks and it implicitly generates progress objects to manage concurrency. Arrowjs can implement a form of push-based reactive programming, where event streams are arrow loops communicating through shared memory. Arrowjs thus provides interoperability between thread-like callback chains and event streams with a uniform concurrency control mechanism.