Builds a binary tree from a sorted array and searches a value using the binary tree (JavaScript)

binary_search.js

function Node(val) {
    this.value = val;
    this.left = null;
    this.right = null;
}

var numList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

function buildTree(list, start, end) {
    if (start > end) {
        return null;
    }

    var center = Math.floor((start + end) / 2);
    var head = new Node(list[center]);

    head.left = buildTree(list, start, center - 1);
    head.right = buildTree(list, center + 1, end);

    return head;
}

var head = buildTree(numList, 0, 9);

//console.log(head);
//console.log(head.left);
//console.log(head.right);

function search(head, num) {
    if (head === null) {
        return null;
    }

    if (num === head.value) {
        return head;
    }

    if (num < head.value) {
        return search(head.left, num);
    } else {
        return search(head.right, num);
    }
}

console.log(search(head, 3));
console.log(search(head, 1));
console.log(search(head, 5));
console.log(search(head, 11));