console.log waits for Web IDE connection when plugged in with data USB cable

Yes, this is a common issue: http://www.espruino.com/Troubleshooting#i-typed-save-but-espruino-won-t-work-or-stops-working-quickly-when-powered-from-a-computer-it-only-works-from-a-usb-power-supply-battery-or-the-computer-when-the-web-ide-is-running-

It's intentional that the board won't drop information if you're connected to USB - because chances are everyone would get upset pretty quick if data that was output just disappeared into thin air if it wasn't read for a second or two

The issue is that from Espruino's point of view it has no way of knowing the difference between:

• USB connected, no app running on PC
  
• USB connected, app running but busy and not reading data
  
• USB connected, app running and reading data just fine (although arguably something could be added to detect a lack of movement of data)
  
  

About all I can suggest is to use a function called log that you set to log=function(){}.

When you connect with the IDE you can then write log = print