In browsers, el.value for an <option> will fallback from getAttribute('value') to the inner content of a node. Since jQuery executes in the browser, it gets this for free when it asks for el.value. However, Cheerio currently does not support this behavior. As a result:

<select><option selected>Hello</option></select>

$('select').val() will return [undefined] via Cheerio and ['Hello'] via jQuery.