Gridview rowcount from Js

I needed to get some rowcont in a Js variable, to have a google-like "select all" (all from all pages) button, that i didn't want to show up if there is only one page in my gridview.

Radu helped me out with this idea:
(I am using this on rowDataBound, because I didn't want to use an other event, I already had this one ...)

ScriptManager.RegisterClientScriptBlock(grvAgentCommissionFeePercentage, this.GetType(), "ScriptIDAndTicksForRefreshnumber" + DateTime.Now.Ticks.ToString(), "multiplePages = " + grvAgentCommissionFeePercentage.PageCount.ToString() + ";", true);

if you need the whole nine yards, just comment ... i'll get back to you