Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<head>
<style>
table, th {
    border: 1px solid black;
}
</style>
</head>
<body>

<p>Click the button to return the value of the headers attribute of each th element in second row.</p>

<table id="myTable">
  <tr>
    <th id="name" colspan="3">Name</th>
  </tr>
  <tr>
    <th headers="fname">First name</th>
    <th headers="mname">Middle name</th>
    <th headers="lname">Last name</th>
  </tr>
</table>
<br>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    var table = document.getElementById("myTable");
    var txt = "";
    var i;
    for (i = 0; i < table.rows[1].cells.length; i++) {
        txt = txt + table.rows[1].cells[i].headers + "<br>";
    }
    document.getElementById("demo").innerHTML = txt;
}
</script>

</body>
</html>