JavaScript autocomplete without external library

Is there a javascript autocomplete library that does not depend on any other libraries?

I am not using jQuery or the likes as I am making a mobile app that I need to keep extra light.

Here is a basic JavaScript example, which could be modified into an autocomplete control:

var people = ['Steven', 'Sean', 'Stefan', 'Sam', 'Nathan'];

function matchPeople(input) {
  var reg = new RegExp(input.split('').join('\\w*').replace(/\W/, ""), 'i');
  return people.filter(function(person) {
    if (person.match(reg)) {
      return person;
    }
  });
}

function changeInput(val) {
  var autoCompleteResult = matchPeople(val);
  document.getElementById("result").innerHTML = autoCompleteResult;
}

<input type="text" onkeyup="changeInput(this.value)">
<div id="result"></div>

For anyone looking at this in 2017 onwards who needs a simple solution, you can use HTML5's built-in <datalist> tag instead of relying on JavaScript.

Example:

<datalist id="languages">
  <option value="HTML">
  <option value="CSS">
  <option value="JavaScript">
  <option value="Java">
  <option value="Ruby">
  <option value="PHP">
  <option value="Go">
  <option value="Erlang">
  <option value="Python">
  <option value="C">
  <option value="C#">
  <option value="C++">
</datalist>

<input type="text" list="languages">

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/datalist