Render an html according to external link

Hi,
I would like to display in a Tab controller implemented by javascript
external site pages.
But I have a problem to render the external sites link as string in
order
to pass it to the tabs panels.

var pane1 = “”? //Here I want to render as string www.foo.com target
var pane2 = “”?//Here I want to render as string www.boo.com target

var ts = new tabstrip();
var t1 = new tab(“Foo”,pane1);
var t2 = new tab(“Boo”,pane2);
ts.add(t1);
ts.add(t2);
ts.add(t3);
ts.add(t4);
ts.add(t5);

ts.write();

How can I render an html according to external link? for example

render_as_string(“http://www.foo.com”)

Thanks
Sharon Lin.