PageDown ACE is a port of PageDown running with ACE editor instead of a textarea.
Basically:
<div id="wmd-button-bar"></div>
<div id="wmd-input"></div>
<script type="text/javascript">
var converter = new Markdown.Converter();
var editor = new Markdown.Editor(converter);
var ace = ace.edit("wmd-input");
editor.run(ace);
</script>The demo page has been updated accordingly.
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