how to pass value from javascript to gridview item template textbox?

i am using popup in gridview itemtemplate which pass value two in returnvalue1 , i am getting value and split to show name only in textbox but save id in back code db. now the problem is , when i click popup it show me itemname on gridview textbox ,i am using button which dynamically add new row, when i click add new row button , then i click popup of new row for itemname , it replace value of previous row textbox value with new value of current row textbox. Please tell me how can i resolve this problem ?![enter image description here][1] .
Please Click this Image Link thanks.
http://i.stack.imgur.com/1nCbd.png
function setValue1(returnValue1) { var table = document.getElementById('<%=GridView1.ClientID%>');
if (table.rows.length > 0) { //loop the gridview table for (var i = 1; i ...