Javascript Trie class

Trie.js

class TrieNode {
	constructor (word) {
		this.word = word;
		this.nodes = {};
		this.end = false;
	}
}

export default class Trie {
	constructor (word) {
		this.root = new TrieNode("");
	}

	insert (word = "") {
		var currentNode = this.root;
		var letter = word.slice(0,1); // get first letter
		word = word.slice(1); // get remainder of word

		var childNode;

		while (letter.length > 0) {
			if (currentNode.nodes[letter] === undefined) {
				childNode = new TrieNode(letter);
				currentNode.nodes[letter] = childNode;
			} else {
				childNode = currentNode.nodes[letter];
			}

			currentNode = childNode;
			letter = word.slice(0, 1);
			word = word.slice(1);
		}

		childNode.end = true;
	}

	search (word = "") {
		var currentNode = this.root;
		var letter = word.slice(0, 1);
		word = word.slice(1);

		while (letter.length > 0) {
			if (currentNode.nodes[letter]) {
				currentNode = currentNode.nodes[letter];
				if (word.length === 0) {
					// if search is longer than nodes, ...
					return currentNode.end;
				}

				letter = word.slice(0, 1);
				word = word.slice(1);
			} else {
				return false;
			}
		}
	}

	startsWith (wordPrefix = "") {
		var currentNode = this.root;
		var letter = wordPrefix.slice(0, 1);
		wordPrefix = wordPrefix.slice(1);

		while (letter.length > 0) {
			if (currentNode.nodes[letter]) {
				currentNode = currentNode.nodes[letter];
				letter = wordPrefix.slice(0, 1);
				wordPrefix = wordPrefix.slice(1);
			} else {
				return false;
			}
		}

		return true;
	}
	
	//TODO: #count (word)
}