WEB exports or downloads the file function code in the modal form

 
<title> My chats </title> 
<base target="_self" /> 
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<script> 
$(document).ready(function() { 
$('a[href][href!="#"]').click(function() { 
SetSelfTarget(this); 
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$('input').click(function() { 
SetSelfTarget(this); 
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function SetTarget() { 
var htmTarget = document.getElementsByTagName("head"); 
if ((undefined != htmTarget) && (0 < htmTarget.length)) { 
var b = htmTarget[0].getElementsByTagName("base"); 
if ((undefined != b) && (0 < b.length)) { 
b[0].target = "download"; 
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} 
function SetSelfTarget(obj) { 
if (obj.id != "btn_Export") { 
var htmTarget = document.getElementsByTagName("head"); 
if ((undefined != htmTarget) && (0 < htmTarget.length)) { 
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if ((undefined != b) && (0 < b.length)) 
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</script> 
<asp:Button ID="btn_Export" runat="server" Text=" export " OnClick="btn_Export_Click" OnClientClick="SetTarget()" />