Help with variables

I am writing test scripts using Webdriver inside of a Pentaho development environment- all code is in javascript.
 I have declared a variable in my js code and now need to put this variable inside a selenium.runScript command for further testing on a web page. 

The variable that I define is not available to the runScript. I guess I need something like a global variable that can cross over between my js and the runScript.

I hope this makes sense! Please provide some help!!!!

var test = 'Test input'
selenium.runScript("tinyMCE.activeEditor.setContent(test);");

I have tried both HTMLUnit and FireFox drivers.

Thanks!