Check if an element is a child of a parent

Question

I have the following code.

Answer 1

Vanilla 1-liner for IE8+:

parent !== child && parent.contains(child);

Here, how it works:

function contains(parent, child) {
  return parent !== child && parent.contains(child);
}

var parentEl = document.querySelector('#parent'),
    childEl = document.querySelector('#child')
    
if (contains(parentEl, childEl)) {
  document.querySelector('#result').innerText = 'I confirm, that child is within parent el';
}

if (!contains(childEl, parentEl)) {
  document.querySelector('#result').innerText += ' and parent is not within child';
}