try like this
<!DOCTYPE html>
<html ng-app="" xmlns="http://www.w3.org/1999/xhtml">
<head>
<script src="Scripts/jquery-1.8.2.js"></script>
<script>
function openfile(obj) {
window.open = obj.innerText;
}
$(function () {
var items = [{ User_Name: 'aa', Score: 23, team: 'aa team' },
{ User_Name: 'bb', Score: 33, team: 'bb team' },
{ User_Name: 'cc', Score: 43, team: 'cc team' }];
var url = 'https://grade.s3.amazon.com/';
var rows = [];
for (var i = 0; i < items.length; i++) {
var item = items[i];
var cols = [];
cols.push('<td>' + item.User_Name + '</td>')
cols.push('<td>' + item.Score + '</td>')
cols.push('<td>' + item.team + '</td>')
cols.push('<td> <a href="#" onclick="openfile(this)" > ' + item.User_Name + '.txt </a> </td>')
rows.push('<tr>'+cols.join('')+'</tr>');
}
$('#tbl tbody').append(rows.join(''));
})
</script>
</head>
<body>
<table id="tbl" border="1" cellpadding="0" cellspacing="0">
<thead>
<tr>
<th>User Name</th>
<th>Score</th>
<th>Team </th>
<th>Download</th>
</tr>
</thead>
<tbody></tbody>
</table>
</body>
</html>
Edit: for downloading file from amazon s3 bucket :
var url = s3.getSignedUrl('getObject',params);