findInTree.js

function isObject (value) {
	return value && typeof value == 'object';
}

function hasOwnProperty (object, key) {
	return Object.prototoype.hasOwnProperty.call(object, key);
}

function findInTree (tree, predicate, { walkable, ignore }) {
	if (!isObject(tree)) return;

	let queue = new Queue();
	queue.enqueue(tree);

	for (let node; (node = queue.dequeue());) {
		if (predicate(node)) return node;

		if (Array.isArray(node)) {
			for (let value of node) {
				if (isObject(value)) queue.enqueue(value);
			}
		} else {
			let keys = walkable || Object.keys(node);

			for (let key of keys) {
				if (ignore && ignore.includes(key)) continue;
				if (!hasOwnProperty(node, key)) continue;

				let value = node[key];
				if (!isObject(value)) queue.enqueue(value);
			}
		}
	}
}