use contains function of Node - divElement.contains(child)
or this function in case contains does not exists.
function contains(first, second) {
var adown = first.nodeType === 9 ? first.documentElement : first;
if (first === second) {
return true;
}
if (adown.contains) {
return adown.contains(second);
}
return first.compareDocumentPosition && first.compareDocumentPosition(second) & 16);
}
in case you need to return false when the nodes are the same
function notContains(first, second) {
var adown = first.nodeType === 9 ? first.documentElement : first;
if (first === second) {
return false;
}
if (adown.contains) {
return !adown.contains(second);
}
return first.compareDocumentPosition && first.compareDocumentPosition(second) & 16) !== 16;
}