<tr>
   <td>
       <span class=1234>My Name is BouncingHippo</span>
   </td>
        ....other well-defined DOM elements with id etc...
 </tr>

function findParentTag(obj, tag) {
    tag = tag.toUpperCase();
    while (obj && obj.tagName !== tag) {
        obj = obj.parentNode;
    }
    return(obj);
}

function changeColor(obj){
    var table = findParentTag(obj, "table");
    var spans = table.getElementsByTagName("span");
    for (var i = 0; i < spans.length; i++) {
        if (spans[i].className) {
            spans[i].style.color = "red";
            break;
        }
    }
}
    ​