Morse code binary tree

morsecode.js

/**
 * Simple morse code translation up to 3 levels deep with uncertainty allowance
 *
 * @example
 * // returns [ 'K', 'O' ]
 * node morsecode.js '-?-'
 *
 * @param {String} input Morse code string containing '-', '.' and '?' characters
 * @returns {String[]} Array of possible value outcomes
 *
 */

class Node {
  constructor(data) {
    this.data = data;
    this["."] = null;
    this["-"] = null;
  }
}

class BinarySearchTree {
  constructor() {
    this.root = new Node(null);
  }

  // Recursively populate tree sequentially
  insert(data, root, index) {
    if (index < data.length) {
      root = new Node(data[index]);

      root["."] = this.insert(data, root["."], 2 * index + 1);
      root["-"] = this.insert(data, root["-"], 2 * index + 2);
    }

    return root;
  }

  traverse(signalArray, nodeArray) {
    // Clone input
    let nodes = [...nodeArray];

    for (const signal of signalArray) {
      const nodePossibilities = [];
      for (let x = 0; x < nodes.length; x++) {
        if (signal === "?") {
          // If signal is unknown, add both child nodes to array
          const left = nodes[x]["."];
          const right = nodes[x]["-"];
          if (left) {
            nodePossibilities.push(left);
          }
          if (right) {
            nodePossibilities.push(right);
          }
        } else {
          // If signal is known, add only that child node to array
          const node = nodes[x][signal];
          if (node) {
            nodePossibilities.push(node);
          }
        }
      }
      // Update node array
      nodes = nodePossibilities;
    }
    // Return mapped possibilities
    return nodes.map(({ data }) => data);
  }
}

const alphabet = " ETIANMSURWDKGO".split("");
const BST = new BinarySearchTree();

BST.root = BST.insert(alphabet, BST.root, 0);

function possibilities(input) {
  const value = BST.traverse(input.split(""), [BST.root]);
  console.log(value);
}

const args = process.argv.slice(2);

possibilities(args[0]);