You may possibly be conflating concurrency and parallelism. JS has concurrency due to its event-based programming model, but not parallelism due to its single-t

You may possibly be conflating concurrency and parallelism. JS has concurrency due to its event-based programming model, but not parallelism due to its single-threaded nature. The TypeScript compilation you mention likely has many concurrently running tasks, just not in parallel (modulo the I/O thread pool as you mention).