recursive solution to leet code problem #108 convert a sorted array into a binary search tree

convertSortedArrayToBinarySearchTree.js

//Definition for a binary tree node; needs to be called with "new"
function TreeNode(val) {
    this.val = val;
    this.right = null;
    this.left = null;
}


var sortedArrayToBST = function(nums) {
    // base cases
    if (nums.length === 1) return new TreeNode(nums[0])
    if (nums.length === 0) return null;

    // create a new TreeNode (center)
    let centerIndex = Math.floor(nums.length/2);
    let root = new TreeNode(nums[centerIndex]);

    // set the left node to center of left subtree
    let leftSubtree = nums.slice(0,centerIndex);
    root.left = sortedArrayToBST(leftSubtree);

    //set the right node to center of the right subtree
    let rightSubtree = nums.slice(centerIndex +1, nums.length);
    root.right = sortedArrayToBST(rightSubtree);

    return root;
};


// test your work!
sortedArrayToBST([-10,-3,0,5,9]); // +. a root node representing this tree will look like: [0,03,9,-10,null,5]