Ace Code Editor

Add to header:

<script src="/ace-builds-1.5.0/src-noconflict/ace.js" type="text/javascript" charset="utf-8"></script>

See ace.c9.io for options and operations.

<div class="row" id="editor" style="width: 100%; height: 200px;" >
<?php
phpinfo();
?>
</div>

<script>
var editor = ace.edit("editor");
editor.setTheme("ace/theme/xcode");
editor.session.setMode("ace/mode/php");
</script>

Example