How to prevent current event's propagation

Think about next scenario:

Create a table.
Each row shows information on click.
Each column shows information on click.
Each column can contain additional clickable tags.

The implementation:

    <table>
        <tr onclick="alert('row');">
            <td onclick="alert('td');">
                <span onclick="alert('td');" style="color:blue;" >
                    Click here!
                </span> 
                &nbsp; td section
            </td>
        </tr>
    </table>

That is because when method is called by any EventListener the event will cease propagating through the tree.

To prevent the propagation after “Click here!” text click use following code:

    <table>
        <tr onclick="alert('row');">
            <td onclick="alert('td');">
                <span onclick="spanClick(event);" style="color:blue;" >
                    Click here!
                </span> 
                &nbsp; td section
            </td>
        </tr>
    </table>
<script>
function spanClick(e)
{    
    alert('span');
    if(!e) var e = window.event;
    try{e.cancelBubble = true; return;}catch(e){} // IE
    try{e.stopPropagation(); return;}catch(e){}   // FireFox
}