test.js

/**
 * Initialize your data structure here.
 */
var Trie = function() {
  this.tries = [];
};

/**
 * Inserts a word into the trie. 
 * @param {string} word
 * @return {void}
 */
Trie.prototype.insert = function(word) {
  this.tries.push(word);
};

/**
 * Returns if the word is in the trie. 
 * @param {string} word
 * @return {boolean}
 */
Trie.prototype.search = function(word) {
  return !!~this.tries.indexOf(word)
};

/**
 * Returns if there is any word in the trie that starts with the given prefix. 
 * @param {string} prefix
 * @return {boolean}
 */
Trie.prototype.startsWith = function(prefix) {
  for (let i = 0; i < this.tries.length; i++) {
    const word = this.tries[i];
    if (word.startsWith(prefix)) return true;
  }
  return false;
};

/**
 * Your Trie object will be instantiated and called as such:
 * var obj = new Trie()
 * obj.insert(word)
 * var param_2 = obj.search(word)
 * var param_3 = obj.startsWith(prefix)
 */