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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 contains(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)); } 

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; } 

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; return first === second || (adown.contains && adown.contains(second) || first.compareDocumentPosition && first.compareDocumentPosition(second) & 16); } 

in case you need to return false when the nodes are the same

function contains(first, second) { var adown = first.nodeType === 9 ? first.documentElement : first; return first !== second && (adown.contains && adown.contains(second) ||   !!(first.compareDocumentPosition && first.compareDocumentPosition(second) & 16)); } 

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 contains(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)); } 

use contains  function of Node
or this function in case contains does not exists.

function contains(first, second) { var adown = first.nodeType === 9 ? first.documentElement : first; return first === second || (adown.contains && adown.contains(second) || first.compareDocumentPosition && first.compareDocumentPosition(second) & 16); } 

in case you need to return false when the nodes are the same

function contains(first, second) { var adown = first.nodeType === 9 ? first.documentElement : first; return first !== second && (adown.contains && adown.contains(second) || !!(first.compareDocumentPosition && first.compareDocumentPosition(second) & 16)); } 

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; return first === second || (adown.contains && adown.contains(second) || first.compareDocumentPosition && first.compareDocumentPosition(second) & 16); } 

in case you need to return false when the nodes are the same

function contains(first, second) { var adown = first.nodeType === 9 ? first.documentElement : first; return first !== second && (adown.contains && adown.contains(second) || !!(first.compareDocumentPosition && first.compareDocumentPosition(second) & 16)); }