caling javascript from codebehind file while using Ajax .

CloseWindow = "alert('sundar')";//we have to call javascript function also.
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "CloseWindow", CloseWindow,true);

following code should be work in the page load time only

Page.RegisterClientScriptBlock("sundar", "")
Page.RegisterStartupScript("sundar", "");