Create a Trie Search Tree

JavaScript
1

Please help me find the error in following code. when i tried to debug it logs ‘this is undefined’ five times.


var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
var Node = function() {
  this.keys = new Map();
  this.end = false;
  this.setEnd = function() {
    this.end = true;
  };
  this.isEnd = function() {
    return this.end;
  };
};
var Trie = function() {
  // change code below this line
  this.root = new Node();
 
  this.add = function(word){
    if(!this.isWord(word) && word != null){
      let chars = word.split('');
      let currNode = this.root;
      for(let char in chars){
        if(!currNode.keys.has(char)){
          currNode.keys.set(char, new Node());
        }
        currNode = currNode.keys.get(char);
      }
      currNode.setEnd();
    }
  }

  this.print = function(){
    let words = new Array();
    let word = '';
    let wordMaker = function(node){
      if(node.isEnd){
        words.push(word);
      }
      if(node.keys.size > 0){
        for(let key in node.keys.keys()){
          word.concat(key);
          wordMaker(node.keys.get(key));
        }
      }
      word = word.slice(0, -1);
    }
    wordMaker(this.root);
    return words;
  }

  this.isWord = function(word){
    if(word != null){
      let chars = word.split('');
      let currNode = this.root;
      for(let char in chars){
        if(currNode.keys.has(char)){
          currNode = currNode.keys.get(char);
        }
        else{
          return false;
        }
      }
      return currNode.isEnd == true;
    }
    return false;
  }
  // change code above this line
};

let tree = Trie();
tree.add('one');
tree.add('oneness')
tree.add('oneder');
tree.print();

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Link to the challenge:
https://learn.freecodecamp.org/coding-interview-prep/data-structures/create-a-trie-search-tree/

1 Like
2

Found many(:cry:) errors:

  1. Quoted function will return Map Iterator. To get array out of it, we have to use

Array.from(node.keys.keys());

  1. Using for by following syntax will loop over an array of keys and not values. To access values we have to use following syntax:

currNode.keys.has(chars(char))

  1. Don’t confuse functions as properties.
1 Like