You want REPL's? We got REPL's!

JavaScript programming desperately needs development tools. Luckily, it's got some.

• Stand-alone command-line JavaScript shell for any Unix, including cygwin
• Web application debugging environment for Firefox
• JavaScript debugger for Firefox
• Web-based JavaScript shell
  

It took me a long, long time to find a command-line shell I could build in Windows with nothing more than ./configure, make, make install.