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.
The "VB Test It" button is for testing VBScript commands.
Select the question mark (?) just after any button for help with that function.