<p>I have a page where my combo box has hundreds of elements which makes it very hard to pick the one item I want. Is there a good Javascript replacement that would do better than</p>

<pre><code>&lt;select id="field-component" name="field_component"&gt; 
                  &lt;option selected="selected"&gt;1&lt;/option&gt;&lt;option&gt;2&lt;/option&gt;...
&lt;/select&gt;
</code></pre>

<p>Is there something with "Intellisense"-like auto-complete?</p>

You have
dhtmlCombo
, using ajax to retrieve data when you are filling the input field.
dhtmlxCombo is a cross-browser JavaScript combobox with autocomplete feature.
It extends basic selectbox functionality to meet the requirements of the most up-to-date web applications.
dhtmlxCombo can be converted from existing HTML SELECT or populated with JavaScript. Supporting AJAX, it can also
get list values from the server datasource dynamically
.