Unable to get property 'textbox1' of undefined or null refer

Hello i am trying to transfer data from webform1 to webform2 how to acheive this using javascript and whn i tried i am getting this error ex:"0x800a138f - JavaScript runtime error: Unable to get property 'textbox1' of undefined or null reference"

following is the code which is under button click event.Thanks

ex:

---

string strtxtid=datagrid.items[0].cells[1].text.trim();

string strtxtname=datagrid.items[0].cells[2].text.trim();

string strSubject=datagrid.items[0].cells[3].text.trim();

strScript += "";

Response.Write(strScript);