<!DOCTYPE html>
<html encoding="utf-8">
<head>
<style>
*{margin:0;padding:0}
input{font:14px Monospace;height:20px;width:160px;}
label{display:inline-block;width:100px;height:20px;}
#pass{position:absolute;left:100px;top:0;opacity:0;filter:alpha(opacity=0);z-index:2;}
form{position:relative;}
#hint_pass{position:absolute;left:100px;}
</style>
</head>
<body>
<form>
<label>Password:</label>
<input type="text" id="hint_pass" maxlength="20" tabindex="-1" />
<input type="text" id="pass" name="pass" maxlength="20" />
</form>
<script>
var pass=document.getElementById('pass');
var hint_pass=document.getElementById('hint_pass');
pass.onkeyup=pass.onchange=function(){hint_pass.value=pass.value.replace(/./g,'*');};
</script>
</body>
</html>