depth first search

class Node {
    constructor (val) {
        this.value = val;
        this.children = [];
    }
}

function depthFirstSearch(seek, node) {
    if (seek === node.value) return node;

    for (let i=0; i<node.children.length; i++) {
        const child = node.children[i];
        const result = depthFirstSearch(seek, child);

        if (result !== -1) {
            return [node].concat(result);
        }
    }

    return -1;
}

const tree = new Node(5);
tree.children.push(new Node(3));
tree.children.push(new Node(4));
tree.children.push(new Node(6));
tree.children[0].children.push(new Node(1));
tree.children[0].children.push(new Node(2));
tree.children[2].children.push(new Node(7));
tree.children[2].children.push(new Node(8));
tree.children[2].children.push(new Node(9));

console.log("Depth First Search");
console.log(1, depthFirstSearch(1, tree).map(obj => obj.value));
console.log(9, depthFirstSearch(9, tree).map(obj => obj.value));
console.log(12, depthFirstSearch(12, tree));