Trie

trie.js

export default class Trie {
  constructor(value = '') {
    this.value = value;
    this.children = [];
  }

  add(value) {
    let parent = this;
    for (let i = 0, len = value.length; i < len; i++) {
      let key = value.slice(0, i + 1);
      let node = parent.find(key);

      if (!node) {
        node = new Trie(key);
        parent.children.push(node);
      }

      parent = node;
    }

    return parent;
  }

  find(search) {
    let node = this;

    let key = '';
    for (let char of search) {
      key += char;
      node = this.children.find(child => child.value === key);
      if (!node) return null;
    }

    return node;
  }
}

The operation .find is O(n) to search. it's better to set this.children={} to achieve O(1) look up

@lienista you are right, there was no real effort to optimize this, but rather the focus was to explain the underlying idea as simple as possible, but perhaps a map would be easier than an array for explanation, too!