previousElementSibling Test of previousElementSibling The result of this test is unknown. fnord test(function() { var parentEl = document.getElementById("parentEl"); var lec = document.getElementById("last_element_child"); var pes = lec.previousElementSibling; assert_true(!!pes) assert_equals(pes.nodeType, 1) assert_equals(pes.getAttribute("id"), "middle_element_child") })