Enter your JavaScript, test it, convert it to a JavaScript command, then select it to cut and paste into a BookMarklet.  The Split button will break existing code into multiple lines so that you may work with it more easily and the Length button tells you the current number of characters and lines in your code.  You may UnDo to return to what you had before the last conversion.  Select the question mark (?) just after any button for help with that function.


           

The following buttons may not be very helpfull for JavaScript code, but may be of use to you in general work:

           
       
     
   

If you're working with Bond, James Bond, you might appreciate these: