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Check if an element is a descendant of another

Written byPhuoc Nguyen
Category
Level 1 — Basic
Created
22 Feb, 2020
Assume that we want to find out if the `child` element is a descendant of the `parent` element.

1. Use the contains method

const isDescendant = parent.contains(child);

2. Go up from the child until see the parent

// Check if `child` is a descendant of `parent`
const isDescendant = function (parent, child) {
let node = child.parentNode;
while (node) {
if (node === parent) {
return true;
}

// Traverse up to the parent
node = node.parentNode;
}

// Go up until the root but couldn't find the `parent`
return false;
};

See also

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Phước Nguyễn