问如何选择只包含一行的所有<pre>？

EN

var myList = $('pre').filter(function(index) {
    var val = $(this).text().trim();
    return val.indexOf('\n') == -1;
});

$.each(myList, function() {
    alert($(this).text());
});​

<pre>hello</pre>

<pre>great
</pre>

<pre>you
say
</pre>

<pre>

yes</pre>

<pre>

heila
</pre>

<pre>not
included</pre>

<pre>included</pre>
​

 hello
 great
 yes
 heila
 included

var myList = $('pre').filter(function(index) {
    var val = $(this).text();
    return val.substring(0, val.length -2).indexOf('\n') === -1;
});