:empty Selector
Select all elements that have no children (including text nodes).
.empty()
This is the inverse of :parent.
One important thing to note with :empty (and :parent) is that child elements include text nodes.
The W3C recommends that the <p> element have at least one child node, even if that child is merely text (see https://www.w3.org/TR/html401/struct/text.html#edef-P). Some other elements, on the other hand, are empty (i.e. have no children) by definition: <input>, <img>, <br>, and <hr>, for example.
Finds all elements that are empty - they don't have child elements or text.
JS
<table border="1">
<tr>
<td>TD #0</td>
<td></td>
</tr>
<tr>
<td>TD #2</td>
<td></td>
</tr>
<tr>
<td></td>
<td>TD#5</td>
</tr>
</table>
CSS
td {
text-align: center;
}
HTML
$("td:empty").text("Was empty!").css("background", "rgb(255,220,200)");
DEMO