Testing objects for ancestor/descendent relationship in JavaScript or Jquery

Question

I\'m trying to come up with a reusable JS or jQuery function that would allow me to test if one object is a DOM descendant of another.

I\'ve seen a model of testing

Answer 1

In jQuery ancestors using jQuery objects I suggested

if ($(obj1).parents().index($(obj2)) >= 0) {
    // obj1 is a descendant of obj2
}

Answer 2

a.contains(b)

This is a pure JavaScript solution using Node.contains. The function is inclusive, a.contains(a) evaluates to true.

There's an edge case in IE9: if b is a text node, contains will always return false.

Answer 3

Try this:

$('#foo').filter(function(){

   return $(this).parent().is('#foo-parent');

});

So here we are selecting all the foo elements and then filtering only the elements that have the foo-parent as their immediate parent.

If you are looking to find if the any of the ancestors of the current object comply to the rule, then I guess it should be:

$('#foo').filter(function(){

   return $(this).parents().is('#foo-parent');

});