Just to clarify things, you don't/can't "execute it within the HTML body".
You can modify the contents of the HTML using javascript.
You decide at what point you want the javascript to be executed.
For example, here is the contents of a html file, including javascript, that does what you want.
<html>
<head>
<script>
// The next line document.addEventListener....
// tells the browser to execute the javascript in the function after
// the DOMContentLoaded event is complete, i.e. the browser has
// finished loading the full webpage
document.addEventListener("DOMContentLoaded", function(event) {
var col1 = ["Full time student checking (Age 22 and under) ", "Customers over age 65", "Below $500.00" ];
var col2 = ["None", "None", "$8.00"];
var TheInnerHTML ="";
for (var j = 0; j < col1.length; j++) {
TheInnerHTML += "<tr><td>"+col1[j]+"</td><td>"+col2[j]+"</td></tr>";
}
document.getElementById("TheBody").innerHTML = TheInnerHTML;});
</script>
</head>
<body>
<table>
<thead>
<tr>
<th>Balance</th>
<th>Fee</th>
</tr>
</thead>
<tbody id="TheBody">
</tbody>
</table>
</body>
Enjoy !