How Do You Create a Trie Data Structure?


Larry Thompson

Creating a Trie Data Structure

In this tutorial, we will explore the creation of a Trie data structure. The Trie, also known as a prefix tree, is an efficient data structure used for storing and searching strings. Its unique design allows for fast retrieval of words and prefixes, making it particularly useful in applications involving dictionaries, autocomplete features, and search engines.

What is a Trie?

A Trie is a tree-like data structure that stores strings. It is composed of nodes, where each node represents a character in the string. The root node represents an empty string, and each subsequent level corresponds to one character of the string.

Structure of a Trie

Each node in a Trie consists of several important components:

  • Value: This represents the character associated with the node.
  • Children: These are pointers to child nodes representing subsequent characters in the string.
  • EndOfWord: This boolean flag indicates whether the current node marks the end of a valid word.

Create a Trie Node

To create a basic Trie node in HTML:

<div class="trie-node">
  <span class="value">a</span>
  <div class="children"></div>
  <span class="end-of-word"></span>

Here we have used <div> tags with appropriate classes to represent different components of the Trie node. Feel free to style them using CSS for better visualization.

Create Insert Function

The insert function adds words to the Trie by traversing through each character and creating new nodes as necessary. Here’s an example of how we can implement it in JavaScript:

function insert(root, word) {
  let currentNode = root;
  for (let i = 0; i < word.length; i++) {
    const char = word[i];
    let childNode = currentNode.querySelector('.children .trie-node[value="' + char + '"]');
    if (!childNode) {
      childNode = document.createElement('div');
      childNode.innerHTML = '<span class="value">' + char + '</span><div class="children"></div><span class="end-of-word"></span>';
    currentNode = childNode;

Here, we use the .querySelector() method to find the appropriate elements and manipulate them accordingly. We also add the CSS class .valid-word to mark the end of a valid word.

Searching in a Trie

To search for a word in a Trie, we traverse through each character, following the path formed by the Trie structure. If we encounter a node that does not exist or the end of word flag is not set, it means that the word is not present.

Create Search Function

Let's create a search function that checks whether a given word exists in the Trie:

function search(root, word) {
  let currentNode = root;
  for (let i = 0; i < word.length; i++) {
    const char = word[i];
    const childNode = currentNode.trie-node[value="' + char + '"]');
    if (!childNode || i === word.length - 1 && !childNode.end-of-word.valid-word')) {
      return false;
    currentNode = childNode;
  return true;

The function checks if each character exists in the Trie and if the final node has the .valid-word class.


Tries are powerful data structures that provide efficient storage and retrieval of strings. By following the steps outlined in this tutorial, you can create your own Trie data structure using HTML and JavaScript. Remember to leverage the styling elements we discussed earlier to make your code visually engaging and organized.

Now that you have a good understanding of Tries, you can explore further by implementing additional functionalities like deleting words, auto-suggestions, or even combining Tries with other data structures for enhanced performance. Happy coding!

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