JavaScript Create function

How can i define following object properties of html and define as a function in javascript that would return some object.

HTML:

<object id="desktop" type="application/x-desktop" width="500" height="200">
 <param name="client_type" value="VISTA" /> </object>
 

I want to acheive something like below in javascript.So that I can call GetDesktop() function from outside of javascript.

JavaScript:

 function GetDesktop()
   {
     object.id = "desktop;
     object.type = "application/x-desktop"
      ....
      ...
     ...
    }
 

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