The contains() method of the Node interface returns a boolean value indicating whether a node is a descendant of a given node, that is the node itself, one of its direct children (Node.childNodes), one of the children's direct children, and so on.
contains()
MDN Reference
The
contains()method of the Node interface returns a boolean value indicating whether a node is a descendant of a given node, that is the node itself, one of its direct children (Node.childNodes), one of the children's direct children, and so on.MDN Reference