I don't know if a realy understod your question but maybe this can help you.
When you double click in the table row you copy the last character to clipboard.
Here is the code that I made:
// You can use any function to copy here
function copyToClipboard(textToCopy) {
    var input = document.createElement("input");
    document.body.appendChild(input);
    input.value = textToCopy;
    input.select();
    document.execCommand("Copy");
    input.remove();
}
function copyLastColumn(tr) {
    copyToClipboard(tr.lastElementChild.innerHTML);
    alert('copied to clipboard');
}
<table border="1">
    <tr ondblclick="copyLastColumn(this)">
        <td>a</td>
        <td>b</td>
        <td>c</td>
  </tr>
    <tr ondblclick="copyLastColumn(this)">
        <td>d</td>
        <td>e</td>
        <td>f</td>
    </tr>
    <tr ondblclick="copyLastColumn(this)">
        <td>g</td>
        <td>h</td>
        <td>i</td>
    </tr>
</table>