Trie JS

trie.js

class Node {
  
  constructor(char, isWordComplete = false) {
    this.char = char;
    this.isWordComplete = isWordComplete;
    this.children = new Map(); // Map<char, Node>
  }
  
}

class Trie {
  
  constructor() {
    this.head = new Node('');
  }

  insert(word) {
    let currentNode = this.head;

    word.split("").forEach((char, i) => { 
      if (currentNode.children.get(char) !== undefined) {
        currentNode = currentNode.children.get(char);
        if (i === word.length - 1) 
          currentNode.isWordComplete = true;
      } else {
        const newNode = new Node(char, i === word.length - 1);
        currentNode.children.set(char, newNode);
        currentNode = newNode;
      }
    });
  }
  
  search(word) {
    let currentNode = this.head;  
    const chars = word.split('');

    for (let i = 0; i < chars.length; i ++) {
      const char = chars[i];
      currentNode = currentNode.children.get(char);

      if (!currentNode)
        return false;

      if (i === word.length - 1)
        return currentNode.isWordComplete;
    }
  }
  
  startsWith(prefix) {
    let currentNode = this.head;
    const chars = prefix.split('');

    for (let char of chars) {
      currentNode = currentNode.children.get(char);
      if (!currentNode)
        return false;
    }
    return true;
  }
  
}

const test = (currentResult, expectedResult) => {
  if (currentResult !== expectedResult) {
    console.log('Error!');
  } else {
    console.log('Success.');
  }
} 

var obj = new Trie();

obj.insert('trie');
obj.insert('levymoreira');
obj.insert('levy');

test(obj.search('trie'), true);
test(obj.search('t'), false);
test(obj.search('a'), false);
test(obj.search('levy'), true);
test(obj.startsWith('tr'), true);
test(obj.startsWith('a'), false);