​x
 
<html>
<head>
<script type="text/javascript">
function selText()
  {
  document.getElementById('password1').select()
  }
</script>
</head>
<body>
​
<form>
<input type="password" id="password1" value="thgrt456" />
<input type="button" onclick="selText()" value="Select text" />
</form>
​
</body>
</html>
​