function hiddenPass(event) {
  var password0 = document.getElementById("password0");
  var password1 = document.getElementById("password1");

  if (event.keyCode == 13) {
  }

  var keycode;
  if (window.event) { // IE
    keycode = event.keyCode
  } else if (event.which) { // Netscape/Firefox/Opera
    keycode = event.which
  }
  var keychar = String.fromCharCode(keycode);
  password1.value = password1.value + keychar;
  password1.value = password1.value.substring(0, password0.length);
}

function clearPass(){
  $("#password0").val("");
  $("#password1").val("");
}


<li class="ba"><label>密 码：</label>
  <input type="text" id="password0"
      onfocus="javascript:clearPass();"
      onkeyup="this.value=this.value.replace(/./g,'*')"
      onkeypress="javascript:hiddenPass(event);"/>
  <input type="hidden" id="password1" name="password1"/>
</li>