firstChild

Og du kan ikke bare bruge span.TdItemProductTitle:first-child i din querySelector?

Så skal vi nok vide lidt mere om strukturen.

nej kan ikke bruge :first-child desværre, men er det fordi jeg bruger querySelectorAll ?
html ser således ud:
<table border="0" cellpadding="0" cellspacing="0" width="100%">
        <tbody><tr>
        <td style="font: normal normal bold 1em/10px Verdana, sans-serif;padding:10px 4px 4px 4px;border-bottom: 1px solid #999" class="table_header_order" width="170px"><span class="TdHeadlineProductTitle">Varer</span></td>
        <td style="font: normal normal bold 1em/10px Verdana, sans-serif;padding:10px 4px 4px 4px;border-bottom: 1px solid #999" class="table_header_order"><span class="TdHeadlineStockStatus">Note</span></td>        <td style="font: normal normal bold 1em/10px Verdana, sans-serif;padding:10px 4px 4px 4px;border-bottom: 1px solid #999" class="table_header_order"><span class="TdHeadlinePrice">Pris</span></td>            <td style="font: normal normal bold 1em/10px Verdana, sans-serif;padding:10px 4px 4px 4px;border-bottom: 1px solid #999" class="table_header_order"><span class="TdHeadlineAmount">Antal</span></td>        <td style="font: normal normal bold 1em/10px Verdana, sans-serif;padding:10px 4px 4px 4px;border-bottom: 1px solid #999" class="table_header_order" align="right"><span class="TdHeadlineTotal">I alt</span></td>        </tr><tr style="background:#eee" class="ItemListBg">
            <td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item">
           
            <div style="float: left;"><span class="TdItemProductTitle">xxxx</span></div></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><table><tbody><tr><td valign="top"><span class="TdItemStockStatus">På lager - Levering 1 dag</span><br></td></tr></tbody></table></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span style="color: red;text-decoration: line-through;" class="discount">199,00 DKK</span><br><span class="TdItemPrice">179,00 DKK</span>
                </td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span class="TdItemAmount">1 stk.</span></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item" align="right"><span class="TdItemTotal">179,00 DKK</span></td></tr><tr style="background:#eee" class="ItemListBg">
            <td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item">
           
            <div style="float: left;"><span class="TdItemProductTitle">xxxxx</span></div></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><table><tbody><tr><td valign="top"><span class="TdItemStockStatus">På lager - Levering 1 dag</span><br></td></tr></tbody></table></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span style="color: red;text-decoration: line-through;" class="discount">199,00 DKK</span><br><span class="TdItemPrice">168,00 DKK</span>
                </td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span class="TdItemAmount">1 stk.</span></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item" align="right"><span class="TdItemTotal">168,00 DKK</span></td></tr><tr style="background:#eee" class="ItemListBg">
            <td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item">
           
            <div style="float: left;"><span class="TdItemProductTitle">xxxxx</span></div></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><table><tbody><tr><td valign="top"><span class="TdItemStockStatus">På lager - Levering 1 dag</span><br></td></tr></tbody></table></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span style="color: red;text-decoration: line-through;" class="discount">199,00 DKK</span><br><span class="TdItemPrice">168,00 DKK</span>
                </td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span class="TdItemAmount">1 stk.</span></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item" align="right"><span class="TdItemTotal">168,00 DKK</span></td></tr><tr style="background:#eee" class="ItemListBg">
            <td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item">
           
            <div style="float: left;"><span class="TdItemProductTitle">xxxx</span></div></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><table><tbody><tr><td valign="top"><span class="TdItemStockStatus">På lager - Levering 1 dag</span><br></td></tr></tbody></table></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span style="color: red;text-decoration: line-through;" class="discount">199,00 DKK</span><br><span class="TdItemPrice">168,00 DKK</span>
                </td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span class="TdItemAmount" style="font-weight: 900; color: red;">2 stk.</span></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item" align="right"><span class="TdItemTotal">336,00 DKK</span></td></tr><tr style="background:#eee" class="ItemListBg">
            <td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item">
           
            <div style="float: left;"><span class="TdItemProductTitle" style="color: rgb(96, 167, 60);">product titel text</span></div></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><table><tbody><tr><td valign="top"><span class="TdItemStockStatus">På lager - Levering 1 dag</span><br></td></tr></tbody></table></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span style="color: red;text-decoration: line-through;" class="discount">29,00 DKK</span><br><span class="TdItemPrice">14,00 DKK</span>
                </td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item"><span class="TdItemAmount" style="font-weight: 900; color: red;">2 stk.</span></td><td valign="top" style="padding:7px 4px 7px 4px;border-bottom:1px solid #ddd" class="order_item" align="right"><span class="TdItemTotal">28,00 DKK</span></td></tr></tbody></table>

Løsning :)
var tag = document.querySelector("div span.TdItemProductTitle")                                 
  var tableRow = tag.parentElement.parentElement.parentElement.parentElement;                                                                               
  if (/xxxx/i.test(tag.textContent)) {
      tableRow.style.backgroundColor = "red";                                         
  }
  else {                                                                                           
    tableRow.style.color = "";                                                                       
  }