Trie

trie.js

var u = require('util');

var strings = ["1234", "hello", "hell", "1el", "1235"];

var trie = {};

function insert (trie, str) {

	var i, ref = trie;

	for (i = 0; i < str.length; i++) {
		if (!ref[str[i]]) ref[str[i]] = {};
		ref = ref[str[i]];
	}	

	ref._ = true;
}

function contains (trie, str) {

	var i, ref = trie;

	for (i = 0; i < str.length; i++) {
		ref = ref[str[i]];
		if (!ref) return false;
	}

	return !!ref._;
}

strings.forEach(function (s) {
	insert(trie, s);
});

console.log(u.inspect(trie, { depth: 10 }));
console.log(contains(trie, 'help'));
console.log(contains(trie, 'hell'));