Register Javascript variables OnLoad from server side

Started out for a way to find ClientId of Asp.Net Button in javascript code.

Interesting find is Page.ClientScript.RegisterClientScriptBlock() which registers variables and allows them to use in javascript on client side.

Sample:
Do the following on Page_Load Event of any page

 var RegisteredVar= string.Format("var _Button1ClientId='{0}';", Button1.ClientID);              Page.ClientScript.RegisterClientScriptBlock(GetType(), "AddScriptVariables", RegisteredVar, true);


Good to use the variable "RegisteredVar" in any javascript function.