[JavaScript] Binary search tree find min height

bst-min-height.js

const assert = require('assert');

// Write function that takes in a non-empty sorted array of distinct integers,
// constructs a BST from the integers, and returns the root of the BST.
function minHeightBst(array) {
  // Find the median of array,
  return constructMinHeightBST(array, 0, array.length - 1)
}

function constructMinHeightBST(array, startIndex, endIndex) {
  if (startIndex > endIndex) {
    return null;
  }
  // Find the median index,
  const medianIndex = Math.floor((startIndex + endIndex) / 2);
  // Create a tree node,
  const bst = new BST(array[medianIndex]);
  // Go left by 1
  bst.left = constructMinHeightBST(array, startIndex, medianIndex - 1);
  bst.right = constructMinHeightBST(array, medianIndex + 1, endIndex);
  return bst;
}

class BST {
  constructor(value) {
    this.value = value;
    this.left = null;
    this.right = null;
  }
  insert(value) {
    // Move to the left branch direction,
    if (value < this.value) {
      // If the left branch is null, create a BST node and attach.
      if (this.left === null) {
        this.left = new BST(value);
      } else {
        // Recursively call for left branch direction,
        this.left.insert(value);
      }
    } else {
      // Move to the right branch direction,
      if (this.right === null) {
        this.right = new BST(value);
      } else {
        this.right.insert(value);
      }
    }
  }
}

// The BST must be balanced to achieve the minimum height.
// - Pick the median integer from array,
// - Divide the array into two slice by that index,
// - left slice divide from median, make the median our left root,
// - rigth slice divide from median, make the median our right root,
// - create insertion list by that,
// - insert that list as BST nodes in correct places.
const array = [1, 2, 5, 7, 10, 13, 14, 15, 22];

// const bst = new BST(5)
// bst.insert(2)
// console.log(JSON.stringify(bst, null, 2));

minHeightBst(array)

shorten.js

function minHeightBst(array) {
  return constructMinHeightBst(array, 0, array.length - 1);
}

function constructMinHeightBst(array, startIndex, endIndex) {
  if (startIndex > endIndex) return null;

  const medianIndex = Math.floor((startIndex + endIndex) / 2);
  const bst = new BST(array[medianIndex]);
  bst.left = constructMinHeightBst(array, startIndex, medianIndex - 1);
  bst.right = constructMinHeightBst(array, medianIndex + 1, endIndex);
  return bst;
}

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

const array = [1, 2, 5, 7, 10, 13, 14, 15, 22];

console.log(JSON.stringify(minHeightBst(array), null, 2));