Find a node matching a predicate in a generic JS tree

findNode.js

function findNode(node, pred) {
    if (pred(node)) {
        return node;
    }

    if (typeof node == 'object' && node.constructor == Object) {
        for (var prop in node) {
            if (node.hasOwnProperty(prop)) {
                let foundNode = findNode(node[prop], pred);

                if (foundNode) {
                    return foundNode;
                }
            }
        }
    } else if (Array.isArray(node)) {
        for (let elem of node) {
            let foundNode = findNode(elem, pred);

            if (foundNode) {
                return foundNode;
            }
        }
    }

    return false;
}