We are developing a JavaScript virtual machine (VM) for embedded systems. The challenge is to reduce the size of the VM and the memory footprint. Our approach is to generate tailor-made VMs, each of which supports only a subset of JavaScript that is necessary and sufficient for the target applications. For this goal, our project is developing a framework to generates specialised VMs. The framework comprises a VM source code generator that generates a specialised VM instruction interpreter and built-in functions from the full-set specifications of JavaScript written in a dedicated domain specific language (DSL), a profiler that collects requirements to the specialised VM for running the target applications, and a customisable runtime system of the VM including object model and garbage collection (GC).