Edit in JSFiddle

$.extend($.expr[":"], {
    exactly: function( element, index, details, collection ){
        return $(element).text() === details[3];
    }
});

$("div:exactly(Foo)").addClass("red");
$("div:exactly(230)").addClass("blu");
<div>Foo</div>
<div>Not Foo</div>
<div>230</div>
<div>230,000</div>
.red {
    color: red;
}
.blu {
    color: blue;
}