I have taught several introductory programming language classes and I really miss the interactive command line interface I had used when I first started teaching. So, I wrote a command line execution environment for JS that actually allows me to interact with JS programs.
You can see a sample execution by going to this page and pressing Enter at the prompt: faculty.ccc.edu/jnadas/js/ijs.htm
[Advanced Technical explanation for gear heads] I created five JS functions: input, print, read, write, and random. When I run an interactive program and hit a new input statement I force an error since there is no way to tell JS to wait for an input. Then, when the user enters a response I store it on a stack and I start executing the program all over again from scratch. I skip any input, print and random statements that I had already executed and only start executing them after I had run out of responses on the input response stack.
Read and Write allows me to simulate file I/O for the students.