Jquery select attribute != includes elements that don't have the attribute

Question

I am trying to select elements that do not match a given attribute id. Based on the following simplified example, why does $("td[groupId != 1]") return elements that do not even have the groupId attribute? Is there another way to select elements that have a groupId where the value is not 1?

<table border="1">
<tr>
    <td>Group 1</td>
    <td groupId="1">1 - 1</td>
    <td groupId="1">1 - 2</td>
    <td groupId="1">1 - 3</td>
    <td>2</td>
    <td groupId="2">2 - 1</td>
    <td>3</td>
    <td groupId="3">3 - 1</td>
    <td>Total</td>
</tr>
<tr>
    <td>1</td>
    <td groupId="1">1</td>
    <td groupId="1">1</td>
    <td groupId="1">1</td>
    <td>2</td>
    <td groupId="2">2</td>
    <td>3</td>
    <td groupId="3">3</td>
    <td>0</td>
</tr>
<tr>
    <td>1</td>
    <td groupId="1">1</td>
    <td groupId="1">1</td>
    <td groupId="1">1</td>
    <td>2</td>
    <td groupId="2">2</td>
    <td>3</td>
    <td groupId="3">3</td>
    <td>0</td>
</tr>
</table>

Answer 1

Try:

$("td[groupId][groupId!='1']")

This type of selector matches all elements with the attribute groupId, but then only chooses the ones where the value is not 1.