title: how to run / debug javascript in command line
body: <p>I'm wondering (actually I know there definitely is such a way to run js in command line, because when I watch google I/0 presentations, they use a command like d8, maybe it's part of V8 engine) is there any way to run/debug my javascripts in command line? such as <code>d8 myJsfile.js --prof</code> etc.?</p>
  
  <p>Does anybody have any idea about this? </p>