Rhino+Dashboard… it’s like crack

If you are a JavaScript junkie who is in constant need of a fix… here’s a little Dashboard trick I like to use to keep an interactive JavaScript prompt available at all times.

(works for Python and Ruby junkies too)

1. Download the WidgetTerm Dashboard Widget. WidgetTerm is basically like Terminal.app in Widget form (although I believe it’s actually based on the open source iTerm application).
2. Download Rhino 1.6… Mozilla’s Java-based implementation of JavaScript 1.5 + E4X + JS interactive interpreter + JS-2-Java bridge.
3. After unpacking Rhino, put its js.jar file on your classpath. If you’re not a Java developer, this is easy… just drop js.jar in ~/Library/Java/Extensions.
4. Now edit this file: ~/.bashrc in your text editor of choice. If it doesn’t exist, just create it. Place the following line in that file:

   
   alias js='java org.mozilla.javascript.tools.shell.Main'
   
   

   Quit and restart Terminal.app (or just source .bashrc). You now have access to a command-line interactive JavaScript interpreter just like the ones provided by Python and Ruby. All you have to do is open a Terminal.app window and type js. BAM… live JavaScript interpreter.

5. Now then… You have installed WidgetTerm right? Good. Activate Dashboard and drag a new WidgetTerm Widget out from the Widget Bar onto the screen. Type js.

There you have it. Now accessing a live JavaScript interpreter is as easy as activating Dashboard.

Since Python and Ruby both have interactive interpreters by default, you can use this trick for them too… I like to have a Python and a JavaScript WidgetTerm open at all times.