Challenge 1: Basic Trie - Insert Method

[Zen-cronic]

My solution for EXERCISE 1 − IMPLEMENTING A TRIE (Chapter 7 in the pdf). After reviewing the author's solution, I've learned to use the insert function itself recursively. Here's my original function where a recursive function inside "insert" method is used:

class TrieNode {
  constructor() {
    this.children = {};
    this.isEndOfWord = false;
  }
}
class Trie {
  constructor() {
    this.root = new TrieNode();
  }

  /**
   *
   * @param {string} word
   */
  insert(word) {
    let i = 0;

    /**
     *
     * @param {TrieNode} currentNode
     * @param {string} currentWord
     */
    const checkFx = (currentNode, currentChar) => {
      //for new char
      if (!Object.keys(currentNode.children).includes(currentChar)) {
        const trieNode = new TrieNode();
        i++;

        currentNode.children = {
          ...currentNode.children,
          [currentChar]: trieNode,
        };

        if (i === word.length) {
          trieNode.isEndOfWord = true;

          return console.log("end of word reached: ", currentChar);
        }

        return checkFx(trieNode, word[I]);

      } else {
        //instead of current node, move on to the child node
        //e.g., e of eaten already exists in root node's children obj

        const childNode = currentNode.children[currentChar];

        //increment to next char
        i++;
        return checkFx(childNode, word[i]);
      }
    };

    checkFx(this.root, word[i]);
  }
}

//test
const trie = new Trie();
trie.insert("cat");
trie.insert("car");
trie.insert("cup");
trie.insert("eat");
trie.insert("eaten");

//log the entire trie object
console.log(JSON.stringify(trie, null, 2));