Really, my favorite editor is...
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta name="viewport" content="width=device-width">
<title>Code Tester</title>
</head>
<body>
<script type="text/javascript">
//<![CDATA[
function preview(){
temp=document.tester.tbox.value;
preWindow=window.open("about:blank", "preWin", "menubar=yes,resizable=yes");
preWindow.document.open();
preWindow.document.write(temp);
preWindow.document.close();
}
//]]>
</script>
<center>
<font face="helvetica" color="#000000">
<h2>< Code Tester ></h2>
<form name="tester">
<textarea rows="22" cols="88" wrap="physical" name="tbox" style="border:1px solid;overflow:auto"></textarea>
<br><hr width="720" size="1" color="#000000" noshade>
<input type="button" value="Test Code" onClick="preview()" style="border:1px solid;background:#FFFFFF;width:200px">
<input type="reset" value="Reset Code" style="border:1px solid;background:#FFFFFF;width:200px">
<br><hr width="720" size="1" color="#000000" noshade>
</form>
</font>
</center>
</body>
</html>
What I did years ago. You can use it freely