In-place Javascript editing addon

Is there any inplace editing addon for Javascript..something like firebug which is very use开发者_运维百科ful for Instant CSS editing and preview, but does not allow inplace JS editing..So, is there any tool or addon where we can instantly update and see Javascript changes ?

Use the console in Firebug. You can type javascript commands in the console that will immediately execute.

You'll notice too in the console that on the far right hand side there's an option to open the command editor which allows you to write multiple lines of javascript before executing.